Step 1: Preheat your oven to 350°F (175°C) to ensure even baking.
Step 2: In a mixing bowl, combine the softened butter, granulated sugar, flour, and vanilla extract. Blend until crumbly.
Step 3: Press the mixture into the bottom of the baking pan. Bake for 15-20 minutes, until edges are golden. Let cool completely.
Step 4: In a saucepan, heat the sweetened condensed milk over medium heat, stirring until thickened and caramel in color (about 5-7 minutes).
Step 5: Pour the toffee filling evenly over the cooled crust and let set for a few minutes.
Step 6: Slice the bananas and layer them over the toffee filling evenly.
Step 7: Spread the whipped cream topping over the bananas for an even finish.
Step 8: Drizzle caramel sauce over the whipped cream if desired.
Step 9: Refrigerate for at least 2 hours to set, then cut into squares and serve.
