Heat oven to 350 degrees F. Line a 13 x 9 x 2-inch baking pan with foil. Coat foil with nonstick cooking spray. Set aside.
In large bowl, whisk cornstarch and sugar until blended. Add cream cheese, and beat until smooth. Beat in eggs, sour cream and milk. Stir in vanilla; set aside
In large microwave-safe bowl, combine butter and chocolate. Microwave for 1 minute, 30 seconds. Stir. If necessary, continue heating in 30-second increments, stirring after each, until chocolate is melted.
Whisk in sugar, then eggs. Whisk in flour, baking powder and salt until smooth. Stir in vanilla and chocolate chips. Spread evenly into prepared pan. Pour cream cheese mixture over brownie mixture. Spread gently until smooth.
Bake at 350 degrees F for 1 hour and 5 minutes or until center is set. Cool on wire rack to room temperature, about 2 hours. Transfer to refrigerator and continue to cool 2 hours.
Heat jelly in microwave-safe bowl for 15 seconds. Stir in berries. Heat fudge sauce in a glass cup in microwave for 25 seconds, until drizzling consistency.
Cut cheesecake brownie into 32 squares. Dollop each square with about 1 tablespoon whipped topping, then some of the strawberries and fudge topping. Sprinkle with nuts, if desired.