Preheat oven to 400 degrees Lightly grease a cookie sheet To make cookie crust In a large mixing bowl cream together 12 cup butter or margarine and white sugar Add egg evaporated milk and vanilla Mix well In a separate bowl mix together flour salt cocoa powder baking soda and baking powder Add flour mixture slowly to sugar mixture while stirring Mix just until all ingredients are combined Drop the dough into greased cookie sheet by rounded tablespoonfuls Leave at least 3 inches in between each one dough will spread as it bakes Bake for 6 to 8 minutes until firm when pressed with finger Allow to cool at least 1 hour before filling
