1 (3 ounce) package baking chocolate, softened
1/2 cup margarine or butter, cooled slightly
3/4 cup white sugar
2 eggs
1 cup sour cream
1/2 cup confectioners' sugar
3/4 cup buttermilk
1/4 cup unsalted butter
1/2 teaspoons vanilla extract
Preheat oven to 400 degrees F (200 degrees C).
In a medium bowl, cream together the margarine or butter with the 2 eggs and the starch. Stir in the sugar and eggs, one at a time, then thoroughly mix in the sour cream, the buttermilk, 1/2 cup of the buttermilk, and the butter.
Drop batter by rounded tablespoonfuls onto small cookie sheets. Bake for 10 to 12 minutes in the preheated oven. Let cool on baking sheet for 3 to 4 minutes before cutting into squares.
To make the Filling: in large bowl combine cream cheese, sugar, eggs, sour cream, confectioners' sugar, buttermilk, and butter. Beat until smooth. Stir in vanilla extract.