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Lava Custard Mooncakes

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Enjoy the Mid-Autumn Festival with these modern Lava Custard Mooncakes. They have a buttery, crumbly cookie-like skin with sweet custard filling and a runny salted egg yolk center that oozes out when cut down in the middle.

lava custard mooncake

The Mid-Autumn Festival is approaching soon. How about trying out these delicious Lava Custard Mooncakes this year?

About Mid-Autumn Festival

The Mid-Autumn Festival, also known as the Moon Festival or Mooncake Festival, is a traditional festival celebrated in Chinese culture. The festival is held on the 15th day of the 8th month of the Chinese lunisolar calendar. On this day, the Chinese believe that the moon is at its brightest and fullest size, coinciding with harvest time in the middle of Autumn.

Making and sharing mooncakes is one of the traditions during the festival. In Chinese culture, a round shape symbolizes completeness and reunion. Thus, the sharing and eating of round mooncakes among family members during the week of the festival signifies the completeness and unity of families.

What Are Lava Custard Mooncakes?

Lava Custard Mooncakes are the modern twist on traditional mooncakes. Traditional mooncakes usually consist of rich thick filling usually made from seed or bean paste surrounded by a thin crust made from lye water and golden syrup. These Lava Custard Mooncakes look similar to the traditional ones on the outside but are made with ingredients that are completely different from the traditional ones. 

lava custard mooncake
lava custard mooncake

These mooncakes have three delectable layers. The outer skin has a buttery, tender, crumbly cookie-like pastry. The middle consists of soft, sweet, and creamy custard filling. And at its core, you will find the sweet and savory salted egg yolk molten lava filling. When you cut the mooncakes in the middle, you will be surprised by the oozing runny filling inside the mooncakes.

modern mooncakes with cookies crust, custard filling, and molten lava salted duck egg yolk filling

Tackling this recipe requires quite a bit of time and preparation, but the satisfaction of slicing open the motel lava core is worth it. These melt-in-your-mouth mooncakes will become a new favorite in your house. Everyone will love them, even those who don’t like the traditional mooncakes! Make a few batches at once and freeze some to gift to others at a later date.

Special Ingredients to Make Lava Custard Mooncakes

  • Salted egg yolks. They are the yolks of salted duck eggs. Salted duck eggs are the result of an age-old method of preserving fresh eggs. Traditionally, they are made by covering eggs with clay made from plant ash, dirt, salt, and water. The eggs are then left to sit for 30 to 40 days. While they sit, water exits the egg and is replaced by salt, in a process known as osmosis. The egg whites turn thick and slimy while the round yolks solidify and turn bright and orange-red in color during the salt curing process. 
  • Custard powder. Custard powder is not dried, powdered custard. It is actually a powdered mix used to make custard, and it is very similar to the type of mix used to make instant puddings. Typically, you can add only water or milk to turn the powder into a custard. Why use custard powder in this mooncake recipe? The custard made with custard powder is more stable and uses less egg which lowers the possibility of curdling. The powder also contains flavorings that make the custard richer and taste better than custard made with just eggs.
  • Milk powder. To enhance the flavor.
  • Evaporated milk. Evaporated milk starts out as fresh milk and is heated to drive off more than half of the water. The resulting liquid is creamier and thicker than regular whole milk. Adding this to baked goods instead of regular milk makes the result taste richer.
  • Condensed milk. To sweeten and add flavor to the custard.

How to Prepare the Salted Egg Yolks 

You can find ready-made vacuum-packed salted egg yolks in some Asian grocery stores, either in the fridge or freezer section. But if possible, find whole salted duck eggs instead because they taste a lot better and the yolks are not squeezed. Salted duck eggs can be made by brining the duck eggs in salt water or covering the eggs with clay made from plant ash, dirt, salt, and water. If you are using the ones covered in clay, you will need to wash the covering clean first.

duck salted eggs

Crack the eggs open into a bowl. Make sure the yolks are orange-red in color. If the eggs smell rotten and the yolks have turned blackish, it means the eggs have gone bad. Discard them. Separate the yolks and clean the white membranes under running water. Spray the yolks with a little alcohol, such as Shaoxing wine, baijiu, and vodka, to remove the fishiness. 

wash salted egg yolks clean

You need to cook the salted egg yolks first before using them for making mooncakes. If cooking the salted egg yolks in a small batch, use the steaming method. Meanwhile, bake them in the oven if you have a lot of salted egg yolks.

  • Steaming method. Add water to a steamer and heat the steamer on medium heat. When the water starts to boil, place a heat-proof bowl or plate containing the salted egg yolks and steam for 8-9 minutes. 
  • Baking method. Place the salted egg yolks on a baking sheet lined with aluminum foil for easy cleanup. Bake in the preheated oven for 10 minutes at 320F/160°C.

Special Equipment You Need

  • Kitchen scaleUse weight measurement instead of volume measurement for the best result.
  • Pastry brush. Use a pastry brush with soft bristles to brush the egg wash thinly on top of the mooncakes. I don’t recommend using a silicone brush for making mooncakes.
  • Mooncake mold. To shape the mooncakes. I use the small 50 gr mold.
  • Spray bottle. It is a must to mist the mooncakes with water first before baking. This will prevent the skin from cracking when baking.

Mooncake Mold Size You Need

For this Lava Custard Mooncakes recipe, you need to use a standard 50gr mooncake mold. I have also succeeded in making these in a 65gr mooncake mold by dividing the dough and filling into 12 pieces instead of 15 pieces.

65gr lava custard mooncakes
65gr Lava Custard Mooncakes

I don’t recommend using bigger size mold as the risk of mooncakes cracking will also increase. The reason is that the lava filling will melt and cause the structure of the mooncakes to collapse during the baking. 

Make These Mooncakes in Advance

This recipe requires a lot of patience. None of the components of mooncakes are particularly difficult, but they all take a bit of time. I recommend taking 3 days to make these mooncakes.

  • Day 1. Make the lava and custard filling. The lava filling takes hours to freeze so I recommend taking a full day to make it.
  • Day 2. Make the skin dough and assemble the mooncakes. The assembled mooncakes also need to be freezed for at least 4 hours before they can be baked.
  • Day 3. Bake the mooncakes.
modern mooncakes with cookies crust, custard filling, and molten lava salted duck egg yolk filling

Pro Tips

  • Make a large batch. Given the time commitment required to make these mooncakes, you may as well make 1-2 batches. They also make great gifts for family and friends.
  • Work the fillings in small batches. The lava will easily melt after being taken out from the freezer. I recommend you take out about 3 lava fillings at one time from the freezer to prevent the other 12 from melting.
  • Work fast. Or the lava filling will melt.
  • Keep the fillings cold-frozen. So handling and shaping will be easier
  • Rest the dough. Cover the dough with plastic wrap and rest for 1 hour. This helps to relax the gluten, making it more elastic. The longer the dough is rested, the easier it is to wrap the filling. Otherwise, you may find it easy to tear or crack.
  • Dust the mooncakes with flour before shaping. This prevents them from sticking to the mold.
  • Apply the egg wash thinly. The egg wash should be brushed only very lightly on the mooncakes to achieve a clear pattern. If you have too much egg wash on the mooncakes, it will blur the pattern. I recommend using a pastry brush with fine bristles which is better at applying the egg wash over the intricate patterns. Do not use a silicone brush because it generally picks up too much egg wash. Clean the excess egg wash on the side of the bowl before brushing the mooncakes.
  • Don’t bake the mooncakes for too long. Longer baking time can cause the mooncakes to crack and collapse.
  • Watch the tutorial video. Make sure you watch the video for a visual guide on how to make these Lava Custard Mooncakes.

How to Store

Let the mooncakes cool down completely and store them in an airtight container. They will last for 3 days at room temperature or up to a week in the refrigerator. The mooncake skin is crisp right after baking and will eventually soften after some time. Reheating is recommended for the best molten lava experience.

For longer storage, I recommend only baking the mooncakes as you need and leaving the rest in the freezer. The frozen unbaked mooncakes will last for months this way.

More Mooncake Recipes

modern mooncakes with cookies crust, custard filling, and molten lava salted duck egg yolk filling
4.7 from 3 votes

Lava Custard Mooncakes

Enjoy the Mid-Autumn Festival with these modern Lava Custard Mooncakes. They have a buttery, crumbly cookie-like skin with sweet custard filling and a runny salted egg yolk center that oozes out when cut down in the middle.
Author: Jaja Bakes
Course: Dessert
Cuisine: Chinese
Servings: 15 mooncakes
Tap or hover to scale!
Prep Time3 hours
Cook Time35 minutes
Total Time3 hours 35 minutes


Lava Filling

  • 3 salted egg yolks, 45 gr
  • 50 gr heavy whipping cream
  • 20 gr salted butter, room temperature
  • 20 gr granulated sugar
  • 10 gr evaporated milk
  • 10 gr milk powder

Custard Filling

  • 2 salted egg yolks, 30 gr
  • 1 egg
  • 75 gr evaporated milk
  • 40 gr milk
  • 40 gr granulated sugar
  • 30 gr milk powder
  • 25 gr custard powder
  • 25 gr salted butter, room temperature
  • 12 gr condensed milk
  • 12 gr cake flour

Mooncake Skin

  • 70 gr salted butter, room temperature
  • 35 gr confectioners’ sugar
  • 12 gr egg yolk
  • 13 gr evaporated milk
  • 130 gr cake flour
  • 12 gr custard powder

Egg Wash

  • 1 egg yolk
  • 1 tbsp water


It is recommended to take 3 days to make the whole Lava Custard Mooncakes recipe:

  • Day 1. Make the lava and custard filling.
  • Day 2. Make the skin and assemble the mooncakes.
  • Day 3. Bake the mooncakes.

Prepare Salted Egg Yolks

  • Crack open 5 salted duck eggs and separate the yolks from the whites. Clean the yolks on running water. Place the yolks on a heat-proof plate or bowl.
  • Spray the yolks with a small amount of Shaoxing wine/baijiu/other alcohol to remove the fishiness.
  • Place the yolks on the preheated steamer and steam on medium heat for 8-9 minutes or until cooked.

Lava Filling

  • Blend 3 steamed salted egg yolks and other ingredients with an immersion blender or blender until smooth.
  • Transfer the mixture to a non-stick frying pan. Heat on low heat and cook until the mixture is just warm to dissolve the sugar. Do not boil.
  • Line a small freezer-friendly container with cling wrap. Transfer the mixture to the container. Freeze for 2-3 hours or until firm to touch.
  • Remove the frozen lava filling from the container. Use a knife to divide it into 15 pieces equally (9-10 gr each). Shape into balls and place them in a freezer-friendly airtight container. Make sure to work fast or the lava filling will melt.
  • Freeze the balls for at least 4 hours or overnight.

Custard Filling

  • Blend 2 steamed salted egg yolks and other ingredients with an immersion blender or blender until smooth.
  • Transfer the mixture to a non-stick frying pan. Heat on low heat. Keep stirring the mixture with a spatula while cooking and cook until it thickens and turns into a dough. Don't overcook or it will turn dry and crumbly.
  • While the dough is still hot, cover with a cling wrap to prevent it from drying out. Once the dough has cooled completely at room temperature, store it in the refrigerator until using it.

Mooncake Skin

  • In a medium bowl, add salted butter and sift in confectioners' sugar. Mix until well combined with a spatula or mixer.
  • Add egg yolk and evaporated milk. Mix until combined.
  • Sift in cake flour and custard powder. Mix until well incorporated.
  • Wrap the dough with a cling wrap and let it rest in the refrigerator for 1 hour.

Assemble The Mooncakes

  • Remove the custard filling from the refrigerator. Divide the custard filling into 15 pieces equally (21-22 gr each). Shape into balls.
  • Take a custard ball and make a deep well in the middle with your thumb. Insert one frozen lava ball into the middle and then close the top and reshape it into a ball. Repeat for the remaining 14 pieces. Make sure to work fast or the lava filling will melt. Just take out 3 lava fillings from the freezer at one time to prevent the lava fillings from melting.
  • Freeze the filled custard back into the freezer until you are ready to assemble the rest of the mooncakes.
  • Remove the skin dough from the refrigerator. Divide the dough into 15 pieces equally (18-19 gr each). Shape into balls.
  • Take 3 fillings out from the freezer at one time to prevent the lava filling inside from melting. Flatten a mooncake skin dough ball with your palms. Place a filling in the middle of it. Lift and stretch the dough over the filling to cover completely, and pinch to seal. Roll between your palms to smooth it out.
  • Dust the balls and inside of the 50 gr mooncake mold with flour. Shake off the excess flour. Place a ball into a mooncake mold and face it down on the working surface. Push hard the mold a few times. Release it to get a mooncake out of it. Repeat with the remaining dough and fillings.
  • Place the mooncakes on a freezer-friendly airtight container or a baking sheet. If using a baking sheet, cover the mooncakes with a cling wrap to prevent freeze burn. Freeze the mooncakes for at least 4 hours or overnight.

Bake The Mooncakes

  • Preheat the oven to 425F/220°C. Line a baking sheet with parchment paper or baking mat.
  • Place the frozen mooncakes on the prepared baking sheet. Spray with water to prevent drying out and cracking in the oven.
  • Bake for 5 minutes. Take the mooncakes out of the oven. Let them cool on the pan for 10 minutes.
  • In a small bowl, mix egg yolk and water until combined to make the egg wash. Dip a pastry brush with soft bristle into the egg wash and wipe the brush on the sides of the bowl to remove the excess. Brush the egg wash on top of each mooncake thinly. Don't brush too much egg wash or it will blur the pattern.
  • Bake for another 8-10 minutes or until golden brown. Don't bake for too long or the mooncakes will crack.
  • For the best lava experience, the mooncakes must be consumed warm. You can also reheat the mooncakes in the oven or microwave to make the filling runny again.



Serving: 1mooncake | Calories: 192kcal | Carbohydrates: 18g | Protein: 4g | Fat: 12g | Saturated Fat: 6g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 3g | Trans Fat: 0.3g | Cholesterol: 130mg | Sodium: 85mg | Potassium: 103mg | Fiber: 0.2g | Sugar: 9g | Vitamin A: 426IU | Vitamin C: 0.4mg | Calcium: 70mg | Iron: 0.4mg
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