1 1/2 cups butter
3 eggs
2 cups all-purpose flour
2 tablespoons baking powder
1/4 teaspoon salt
1/2 cup milk
3 tablespoons cornstarch
1/3 cup milk
3 tablespoons cream of tartar
1 teaspoon vanilla extract
1 tablespoon coffee flavored extract
Preheat oven to 350 degrees F (175 degrees C). Grease cookie sheets.
Melt butter in a medium bowl using the whisk and a pastry blender. Mix together the eggs, flour, baking powder, salt and 1/2 cup of the milk so that it is just blended. Stir egg mixture into the milk mixture to form a dough. Roll into 1 inch balls. Place on the prepared cookie sheet.
Bake for 8 to 9 minutes in the preheated oven. Remove from oven and allow to cool slightly. Remove from cookies and place on a wire rack to cool completely. Place 1 teaspoon of coffee extract in the center of each cookie. Press it over the filling to make a dent, about 1 teaspoon at a time, allowing the filling to drain. Cool completely on a wire rack.