In a medium-sized bowl, mix cocoa butter and sugar.
Mix in egg yolks and milk.
Gradually mix in dry ingredients until just combined.
Roll cookies into quarter-sized balls and place them on ungreased cookie sheets, leaving 3/4" between cookies. If you find that the batter becomes difficult to work with in later batches, periodically mix it at high speed to warm it up.
Bake for about 7 minutes. The cookies will still be soft when you remove them from the oven, but will harden as they cool.