Cookies:

• 1 cup white sugar
• 1 cup butter, softened
• 1 (3 ounce) package cream cheese, softened
• 1/2 teaspoon salt
• 1 teaspoon vanilla extract
• 1 egg yolk
• 2 1/4 cups all-purpose flour

In a large bowl, combine the sugar, butter, cream cheese, salt, vanilla extract and egg yolk. Beat until smooth. Stir in flour until well blended. Chill the dough for 8 hours, or overnight. Preheat oven to 375 degrees F (190 degrees C). On a lightly floured surface, roll out the dough 1/3 at a time to 1/8" thickness, refrigerating remaining dough until ready to use. Cut into desired shapes with lightly floured cookie cutters. Place 1 inch apart on ungreased cookie sheets. Leave cookies plain for frosting, or brush with slightly beaten egg white and sprinkle with candy sprinkles or colored sugar. Bake for 7 to 10 minutes in the preheated oven, or until light and golden brown. Cool cookies completely before frosting.

Buttercream Frosting:

• 1/4 cup margarine
• 1/4 cup shortening
• 1/8 teaspoon salt
• 1 teaspoon vanilla extract
• 2 1/2 cups confectioner's sugar
• 2 tablespoons milk

In a large bowl, cream margarine and shortening until light and fluffy. Add salt, vanilla, confectioner's sugar and milk. Beat well.