Crust:
3 1-ounce squares unsweetened chocolate, chopped
1/4 cup butter or margarine, cut into small pieces
2 eggs
1 cup firmly packed brown sugar
1-1/2 teaspoons vanilla extract
2 1-ounce squares semisweet chocolate, finely chopped
1/2 cup self-rising flour

Filling:
1 8-ounce package cream cheese, softened
1/2 cup firmly packed brown sugar
3 eggs
1/2 cup sour cream
1-1/3 cups creamy peanut butter
1/4 cup self-rising flour

Topping:
3/4 cup sour cream
1 tablespoon sugar

Crust:
Preheat oven to 350°F. Grease a 9-inch springform pan with butter. In a small saucepan, melt unsweeetened chocolate with butter, stirring until mixture is smooth. Cool. In a medium bowl, beat eggs and brown sugar until thick and lemon-colored. Beat in chocolate mixture, vanilla, and chopped chocolate. Stir in flour until just blended. Spread 1 cup batter over the bottom of prepared springform pan. Bake for 17 minutes or until firm. Place in freezer for about 15 minutes.

Filling:
In a large mixing bowl, beat cream cheese and brown sugar until smooth. Add egg, sour cream, peanut butter and flour; beat until well blended. With a knife, spread remaining brownie batter around the sides of the pan, sealing batter to bottom crust. Pour in filling. Bake 50 minutes or until center of cheesecake is gently set.

Topping:
In a small bowl, combine sour cream and sugar; blend well. Spread on top of cheesecake to within 3/4-inch of edge.
Bake for 3 minutes.