Step 1: Prepare your pan by greasing it with butter or lining it with parchment paper. This will make it easier to remove the bars later.

Step 2: In a small bowl, combine the graham cracker crumbs and 2 tablespoons of melted butter. Stir until the crumbs are fully coated, then press this mixture into the bottom of your prepared pan to create a crust layer. Use the back of a spoon or the bottom of a glass to press it down firmly.

Step 3: In a large saucepan over medium-low heat, melt the remaining 4 tablespoons of butter. Add the mini marshmallows and stir constantly until fully melted and smooth.

Step 4: Remove the pan from the heat and immediately stir in the dry banana cream pudding mix and vanilla extract. Stir well until the pudding powder is fully dissolved into the marshmallow mixture.

Step 5: Add the Rice Krispies cereal and mix quickly, making sure all the cereal is coated evenly.

Step 6: Working quickly, pour the mixture over the graham cracker crust and press it into an even layer using a spatula or wax paper. If it starts to stick, lightly butter your hands or spatula for easier handling.

Step 7: Let the bars cool at room temperature for at least 30 minutes, or until firm enough to slice. Once set, cut into squares and serve as-is, or top with whipped cream, banana chips, or a drizzle of melted white chocolate.