01 -
Beat the butter and powdered sugar together until smooth and creamy, about 3 minutes. Add in the egg yolks, salt, and vanilla, and mix until it all comes together.
02 -
Split the mixture evenly into two sections. Add 1 1/4 cup flour to one for the plain dough. Mix in 1 cup flour and cocoa powder for the chocolate dough.
03 -
Take small bits, about 1/4 teaspoon, from each dough and roll them into tiny round balls.
04 -
Place three light and three chocolate balls in a pattern like a flower, alternate the colors, press gently, and roll them together into a spiral.
05 -
Press the swirls to flatten a little, then set them on a lined baking tray. Chill them for 15–30 minutes. Bake in a 325°F oven for 13–15 minutes, or until the edges just start browning.