1 cup butter, softened
1 cup sugar
2 egg yolks
1 teaspoon vanilla extract
2 cups flour

Frosting:
½ cup butter, softened
1 (8-oz) package cream cheese, softened
1 (1-lb) box powdered sugar
1 teaspoon vanilla extract
Semi-sweet chocolate chips for topping

In large bowl, cream together butter and sugar. Add egg yolks one at a time, beating well after each addition. Add vanilla and flour and mix well. Cover and chill for one hour. While cookie dough chills, make frosting. In separate bowl, beat butter and cream cheese until smooth and creamy. Add powdered sugar gradually, beating until smooth after each addition. Stir in vanilla and set aside. Preheat oven to 300 degrees. Roll chilled cookie dough into tablespoon-sized balls and place on lightly buttered cookie sheets. Flatten each ball until they are about 1/4-inch think. Bake for 10 to 15 minutes or until lightly browned. Cool completely on wire racks. Spread frosting on each cookie and top with chocolate chips.

Makes about 2 dozen cookies.