Step 1: Prepare the Banana Pudding

1. In a medium saucepan, whisk together the milk, granulated sugar, cornstarch, and salt.
2. Place the saucepan over medium heat and cook while stirring constantly. The mixture will gradually thicken. This should take about 5-7 minutes.
3. Once the mixture thickens and starts to bubble, remove it from the heat. Stir in the vanilla extract.
4. Allow the pudding to cool for about 15 minutes. It will continue to thicken as it cools.
5. Once cooled, gently fold in the sliced bananas.
6. Finally, fold in the whipped topping until everything is well combined. Set aside.

Step 2: Prepare the Strawberry Sauce

1. In a small saucepan, combine the chopped strawberries, granulated sugar, and lemon juice.
2. Cook over medium heat, stirring frequently, for about 5-7 minutes. The strawberries should break down, and the sauce should slightly thicken.
3. Remove from heat and allow to cool. If a smoother consistency is desired, the sauce can be blended or mashed.

Step 3: Prepare the Crunch Topping

1. In a small bowl, mix together the crushed vanilla wafers or graham crackers, melted butter, brown sugar, and crushed strawberries (if using).
2. Stir until the ingredients are well combined and have a crumbly texture.
3. Set aside until ready to assemble the dessert.

Step 4: Assemble the Dessert

1. In a trifle dish, glass bowl, or individual serving cups, begin by layering half of the banana pudding mixture at the bottom.
2. Spoon a layer of strawberry sauce over the pudding.
3. Repeat with another layer of banana pudding, followed by another layer of strawberry sauce.
4. Generously sprinkle the crunch topping over the top.
5. Cover and refrigerate the dessert for at least 1-2 hours before serving. This allows the flavors to meld together and enhances the overall texture.