In a medium bowl, combine the instant vanilla pudding mix, cold milk, and vanilla extract. Whisk together until smooth and thickened, about 2 minutes.
In a separate bowl, mix the graham cracker crumbs, sugar, and melted butter until well combined.
In a 9x9 inch dish, layer half of the graham cracker mixture on the bottom.
Spread half of the pudding mixture over the crumbs, followed by half of the sliced strawberries and bananas.
Repeat the layers with the remaining ingredients.
Top the final layer with whipped topping and garnish with additional sliced strawberries and banana if desired.
Cover the dish with plastic wrap and refrigerate for at least 2 hours before serving to allow the flavors to meld.