If using a cake mix, bake the cake according to the package instructions in a 9x13-inch pan. Allow the cake to cool completely. If using a pre-baked angel food cake, skip this step.
Cut the cooled cake into 1-inch cubes.
Make the Pudding:
In a large bowl, whisk together the instant pudding mix, cold milk, and vanilla extract (if using) until the mixture is smooth and thickened. Set aside.
Layer the Dessert:
In a large punch bowl or trifle dish, start by layering half of the cake cubes on the bottom.
Next, layer half of the sliced strawberries over the cake cubes.
Pour half of the prepared pudding over the strawberries, spreading it evenly.
Spread half of the whipped topping over the pudding layer.
Repeat the layers with the remaining cake cubes, strawberries, pudding, and whipped topping.
Chill:
Cover the punch bowl or trifle dish with plastic wrap and refrigerate for at least 2 hours, or overnight, to allow the flavors to meld and the dessert to set.
Serve:
Garnish with additional sliced strawberries and fresh mint leaves just before serving, if desired.