Brownie Peanut Butter Cheesecake

Crust:
3 1/2 oz. semisweet chocolate, grated (reserve 1/2 oz.)
1/4 C. butter
1/2 C. all-purpose flour
1/8 tsp. baking powder
2 large eggs
1 C. packed light brown sugar
1 1/2 tsp. chocolate extract

Filling:
12 oz. cream cheese, room temperature
1 C. packed light brown sugar
3 large eggs
1/2 C. sour cream
1 1/3 C. creamy peanut butter

Topping:
3/4 C. sour cream
2 tsp. granulated sugar
1/2 C. creamy peanut butter

Preheat oven to 350º F. Lightly grease and flour a 9- or 10-inch springform pan.

Crust:
In the top of a double boiler, over simmering water, melt 3 ounces of the chocolate and the butter, stirring until smooth. Remove from heat.

Combine the flour and baking powder.

In a medium bowl, with electric mixer on medium, beat the eggs until thick and light-colored. Beat in the brown sugar until well blended. Beat in the melted chocolate, chocolate extract, and remaining 1/2 ounce of grated chocolate. Gradually stir in the dry ingredients, mixing just until blended. Spread 1 cup evenly onto bottom of the prepared pan. Chill the remaining crust mixture. Bake for 15-17 minutes, or until firm. Cool in the pan in the refrigerator for 15-30 minutes.

Filling:
In a large bowl, with electric mixer at medium, beat the cream cheese and brown sugar until smooth. Beat in the eggs and sour cream. Beat in the peanut butter.

To prepare the pan, use a spatula to spread the remaining chilled crust evenly around the insides of the pan. To make this easier, set the pan on its side and roll it, spreading at the same time. Pour in the filling mixture.

Bake for 25-30 minutes, or until the filling is firm, spreading the topping on the cheesecake about 3 minutes before removing from the oven.

Topping: In a small bowl, with electric mixer on medium, mix the sour cream, sugar, and peanut butter until smooth. Spread evenly over the top of the cake in the oven 2-3 minutes before it is removed. Cool on a wire rack for 1 hour. Place in a plastic or paper bag and chill overnight.