a. In a microwave-safe bowl, melt the semi-sweet chocolate chips for about 30 seconds, stirring until smooth.

b. In a separate microwave-safe bowl, melt the unsalted butter until fully liquified.

c. In a medium-sized mixing bowl, combine the chocolate wafer crumbs with the melted butter and melted chocolate. Mix well until the crumbs are evenly coated.

d. Press the mixture firmly into the bottom of a 9-inch springform pan, creating an even and compact crust.

e. Place the pan in the refrigerator to chill while preparing the filling.

a. In a large mixing bowl, beat the softened cream cheese until smooth and creamy.

b. Gradually add the heavy whipping cream to the cream cheese, mixing until fully incorporated.

c. Add the sugar and flour to the mixture, continuing to beat until smooth.

d. Beat in the eggs and egg whites, one at a time, ensuring each addition is well combined.

e. Carefully fold in the black raspberry preserves, distributing them evenly throughout the filling.

a. Preheat the oven to 325°F (160°C).

b. Remove the springform pan from the refrigerator and wrap the bottom with aluminum foil to prevent any leaks.

c. Pour the filling into the prepared crust in the pan, smoothing the top with a spatula.

d. Place the pan on a baking sheet and bake in the preheated oven for about 1 hour and 30 minutes to 1 hour and 45 minutes or until the edges are set, and the center is slightly jiggly.

Preparing the Topping:

a. In a medium-sized saucepan, combine the fresh berries, sour cream, sugar, Chambord (black raspberry liquor), and lemon juice.

b. In a small bowl, dissolve the cornstarch in a small amount of water to create a slurry.

c. Bring the berry mixture to a gentle boil over medium heat, stirring constantly.

d. Add the cornstarch slurry to the berry mixture, stirring continuously until the sauce thickens.

e. Remove the saucepan from the heat and allow the berry topping to cool.

a. Once the cheesecake has cooled, release the springform pan's sides and transfer the cheesecake to a serving plate.

b. Pour the prepared berry topping over the cheesecake, spreading it evenly with a spoon or spatula.

c. For the best results, refrigerate the cheesecake for at least 4 hours or overnight to allow it to set completely.

d. Slice the Black Raspberry Cheesecake into wedges and serve, garnishing with extra fresh berries if desired.