I had three leftover egg yolks to use and a lot of chocolate frosting. Cinnamon and chocolate being a great flavor combination, I decided to make these very simple cinnamon cookies and sandwich two together with the leftover chocolate buttercream.

CINNAMON COOKIES
After chilling the dough, preheat oven to 350F/175C.
1 cup sugar
1/2 cup butter
3 egg yolks
2 tablespoons milk
2 cups flour
2 teaspoons cinnamon
½ teaspoons baking powder
½ teaspoons salt

In a medium bowl, combine butter and sugar. Beat in the egg yolks, then stir in the milk. Combine flour, cinnamon, baking powder and salt. Stir dry mixture into the wet ingredient mixture. Wrap dough in plastic wrap and chill for at least two hours.

Preheat the oven. Roll out dough on a lightly floured surface. Roll to about ¼ inch thickness. Cut into shapes and place about 1 inch apart on cookie sheets. (I cut into circles using the edge of a glass).
Bake 10-12 minutes. Let sit on pan for a minute or two after removing from oven. Transfer to wire rack for thorough cooling.