Chocolate Cheesecake Squares

1 cup flour
1/2 cup sugar
3 tbsp baking cocoa
1 tsp baking powder
1/4 tsp salt
1/2 cup cold butter
1 egg yolk
1 tsp vanilla
1/2 cup finely chopped walnuts

Filling:
1 pkg (8 ounces) cream cheese, softened
1/3 cup sugar
1/2 cup sour cream
1 tbsp flour
2 tsp grated orange peel
1/4 tsp salt
1 egg
1 egg white
1/2 tsp vanilla
Chocolate sprinkles, optional

Line a 9 inch square baking pan with foil. Grease the foil. Set aside. In a
large bowl, combine the first five ingredients. Cut in the butter until the
mixture resembles fine crumbs. Stir in the egg yolk, vanilla, and walnuts.
Press onto the bottom of the prepared. Bake at 325 F for 15 minutes. In a
small bowl, beat the cream cheese and the sugar until smooth. Beat in the sour
cream, flour, orange peel, and salt. Beat in the egg, egg white, and vanilla on
low speed just until combined. Pour over the warm crust. Bake for 20-25
minutes or until the center is almost set. Cool on a wire rack for 1 hour.
Garnish with some chocolate sprinkles if desired. Refrigerate overnight. Using
the foil, lift out of the pan. Remove the foil. Cut into 1 inch squares.
Makes about 2 dozen