Found on the internet many years ago, link lost to the world.
1/2 c. butter
3/4 c. sugar
1 tsp. pure vanilla extract
1 1/2 c. flour
1/2 c. cocoa
1/2 tsp. baking powder
1/2 tsp. baking soda
1/4 tsp. salt
Combine all dry ingredients in a bowl. Set aside. In another large bowl, combine butter, sugar, egg and vanilla and mix with an electric mixer until fluffy. Add dry ingredients bit by bit to mixer bowl, and blend until well mixed. Chill dough for at least 1 hour. When ready to prepare hamentashen, divide the dough into quarters. Roll into 1/4-inch thickness on a lightly floured board. Cut out 3-inch rounds using the lip of a small glass held upside-down. Reroll scraps until dough is finished. Place filling in the center of each dough round. Fold three sides up to form a triangle, leaving some filling exposed in the center.
Preheat oven to 350 degrees. Place cookies approx. 2 in. apart on lightly greased cookie sheets. Bake for 15-17 minutes or until golden. Transfer to a wire rack to cool.
Fillings: chocolate chips, orange marmalade, raspberry preserves