In a large bowl, add unsalted butter and sift in the confectioners' sugar. Mix with a spatula or hand mixer until well combined.

Add vanilla extract. Mix until combined.

Sift in the flour and salt. Mix until well combined. The dough will look crumbly at first, but it will come together as you continue mixing.

Divide the dough into 2 bowls evenly. Sift in matcha powder into a bowl and mix until well combined with a spatula. Sift in taro powder into the other bowl and mix until well combined.

If the dough is too sticky to handle, refrigerate it for 20 minutes until just a little bit firmer.

Take half of the matcha dough and flatten it with your hand into a rough 6x3-inch/15x7.5 cm rectangle. Put the flattened dough onto a floured work surface. Take half of the taro dough and flatten it again into the same size rectangle. Put the flattened taro dough on top of the flattened matcha dough. Repeat the entire process so you have 4 alternating layers. (See the video for the visual guide)

Cut the layered dough vertically in the middle with a sharp knife. Then, put one part overlay the other. Press and pat the dough into a rough 6x3-inch/15x7.5 cm rectangle. Cut vertically in the middle and stack the dough again. Press the dough into a rectangle log about 1.5x2-inch/4x5cm wide. (See the video for the visual guide)

Wrap the dough with parchment paper or plastic wrap. If the dough is too long, you can divide it into two and wrap them individually. Chill until very firm for at least 2 hours.

Slice the log into a 1/8 to 1/4-inch or about 3-5mm thick with a sharp knife. Arrange the slices on the baking pan, spacing 1.5-inch apart.

Bake for 18-20 minutes or until the bottom edges of the cookies are golden brown in color. Rotate the baking sheets halfway through for even baking.

Transfer to a cooling rack to cool completely.