Bake the Cake: Follow the instructions on the cake mix box to bake the vanilla or angel food cake. Once baked, let the cake cool completely. Then, cut it into bite-sized cubes (about 1-inch pieces).
Prepare the Whipped Cream: In a mixing bowl, whip the heavy cream with a hand mixer or stand mixer until soft peaks form. Add the powdered sugar and vanilla extract, and continue whipping until stiff peaks form. Set aside.
Make the Pudding: In a separate bowl, combine the milk and instant vanilla pudding mix. Whisk until smooth and thickened, about 2 minutes. Stir in the sour cream if using, for extra richness and creaminess.
Macerate the Strawberries: In a small bowl, combine the sliced strawberries with granulated sugar. Toss them gently and let them sit for about 15-20 minutes to release their juices and become syrupy.
Assemble the Cake: In a large punch bowl, layer the ingredients starting with a portion of the cake cubes at the bottom. Add a layer of the macerated strawberries with some of their juice, followed by a layer of the pudding mixture. Then, add a layer of whipped cream.
Repeat Layers: Repeat the layers, starting with cake cubes, followed by strawberries, pudding, and whipped cream, until all the ingredients are used. You should end with a layer of whipped cream on top.
Chill the Cake: Cover the punch bowl with plastic wrap and refrigerate for at least 4 hours, or preferably overnight. This allows the flavors to meld and the cake to absorb some of the strawberry juice, making it even more delicious.
Serve: Before serving, garnish the top with whole strawberries or additional sliced berries if desired. Serve chilled.
