Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
                        -----Brownie Crust-----
   3      Ounces        Unsweetened Chocolate -- chopped
     1/4  Cup           Unsalted Butter -- cut in small pieces
     1/2  Cup           Flour
     1/8  Teaspoon      Baking Powder
   2                    Eggs
   1      Cup           Light Brown Sugar -- firmly packed
   1 1/2  Teaspoons     Vanilla
   2      Ounces        Semisweet Chocolate -- finely chopped
                        -----Filling-----
   8      Ounces        Cream Cheese -- softened
     1/2  Cup           Light Brown Sugar -- firmly packed
   3                    Eggs
     1/2  Cup           Sour Cream
   1 1/3  Cups          Creamy Peanut Butter
     1/4  Cup           Flour
                        -----Topping-----
     3/4  Cup           Sour Cream
   3      Teaspoons     Sugar

Preparation:

For the crust: Preheat oven to 350. Grease a 9-inch springform pan. Dust with flour. Melt unsweetened chocolate and butter in small saucepan over low heat. Cool. Beat eggs and sugar in medium bowl until slowly dissolving ribbon forms when beater are lifted, about 4 minutes. Beat in melted chocolate mixture, vanilla, and chopped chocolate. Add flour and baking powder. Mix until just blended--do not overbeat. Spread 1 cup brownie batter over bottom of pan. Bake until firm, about 17 minutes. Cool baked crust in freezer for about 15 minutes. Maintain oven temperature. For the filling: Blend cream cheese and sugar until smooth. Add eggs and sour cream. Add peanut butter and flour. Using small knife, spread remaining brownie batter around the sides of the pan, sealing batter to bottom crust. Pour in filling, which will not be as high as brownie batter. Bake until center of cheesecake is gently set and brownie sides have fallen to form a ring around the filling. (About 50 minutes) For topping: Blend sour cream and sugar. Spread on top of cheesecake to within 3/4 inch of edge. Bake cheesecake 3 more minutes.