In a bowl mix flour, sugar, egg yolks, vanilla and butter.

Gently knead your hands until the mixture is smooth.

Divide the dough into 3 parts, take 1 part mixed with 5g cocoa powder.

Knead for a uniform cocoa powder.

Put the dough in the fridge to rest for about 45 minutes. Then bring out the dough, rolling flat rolling dough to layer thickness is 3 – 5mm proof. Then use a rectangular biscuit cutter to cut the yellow batter into many cookie crust.

Place a cookie crust on the bottom and then fill with dark chocolate. Note that you should cut dark chocolate so that it is smaller than the crust.

With the top of the cookie, use the shape or number cut in the center of the dough.

The cocoa powder, after resting in the refrigerator, is also rolled out like a yellow powder, then used to cut the cake into different shapes and letters.

Now just gently place the cut brown dough into the center of the biscuit cracked above.

Finally, place the piece of dough just stacked on top, and spread the edges to seal each cookie.

Bring the cake to the refrigerator for about 10 – 15 minutes while heating the grill to 180 degrees C. Then bake the cake for about 10 minutes or until the edge of the yellow cake is rusty.