With a stand mixer fitted with a paddle attachment or a hand mixer, cream together butter, shortening, granulated sugar, and light brown sugar for 2-3 minutes on medium-high speed. Scrape down the sides of the bowl with a spatula.

Add eggs and beat on medium-high heat for 2-3 minutes. Scrape down the sides of the bowl once more.

Turn the mixer on low speed. Stream in the buttermilk, grapeseed oil, and clear vanilla extract. Increase the speed to medium-high speed and paddle for 4-6 minutes until the mixture is light, fluffy, and no streaks of fat or liquid remain. Stop the mixer and scrape down the sides of the bowl.

Turn the mixer on low speed. Sift in the cake flour, baking powder, and salt. Add the 50 gr rainbow sprinkles. Mix just until the batter comes together. Scrape down the sides of the bowl.

Pour the batter into the prepared pan. Using a spatula, spread the batter in an even layer. Sprinkle with the remaining 25 gr rainbow sprinkles evenly on top of the batter.

Bake for 30-35 minutes or until a toothpick inserted into the middle of the cake comes out clean.

Cool completely before assembling the cake.

With a stand mixer fitted with a paddle attachment or a hand mixer, add granulated, light brown sugar, and rainbow sprinkles. Sift in cake flour, baking powder, and salt. Mix on low heat until well combined.

Add grapeseed oil and clear vanilla extract. Mix until small clusters form.

Pour the crumb n the prepared pan. Use your hands to make larger lumps.

Bake for 15 minutes.

With a stand mixer fitted with a paddle attachment or a hand mixer, cream together butter, shortening, and cream cheese for 2-3 minutes on medium-high speed until smooth and fluffy. Scrape down the sides of the bowl with a spatula.

Add glucose, corn syrup, and clear vanilla extract. Beat on medium-high heat for 2-3 minutes until smooth and glossy. Scrape down the sides of the bowl.

Sift in confectioners' sugar and salt. Add baking powder and citric acid. Mix on low speed just to incorporate them into the batter. Turn the speed on medium-high and beat for 2-3 minutes until white and smooth.

In a small bowl, combine milk and vanilla extract until well combined.

Place a parchment paper or silpat onto the counter. Invert cake onto it. Peel off the parchment/silpat from the bottom of the cake.

Use the cake ring to stamp out 2 circles. These will be your middle and top layers. The remaining cake scrap will come together to make the bottom layer of the cake. (*see Video for visual guide)

Put the cake scraps together inside the ring and use the back of your hand to tamp the scraps together into a flat even layer.

Using the back of a bent spoon or ladle, spread 1/5 of the frosting in an even layer over the cake. Sprinkle 1/3 of the crumb over the frosting. Spread 1/5 of the frosting over the crumble into an even layer.

Tuck the second strip of acetate between the cake ring and the top 1/4-inch of the first strip of acetate, so that you have a clear ring of acetate 5 to 6-inches tall.

Top with the remaining crumb.

Transfer the cake to the freeze and freeze for a minimum of 12 hours.

At least 3 hours before serving, remove the cake from the freezer. Remove the cake ring. Transfer the cake to a platter or cake stand. Let it defrost in the fridge. Peel off the acetate before serving.