Preheat & Prep: Preheat your oven to 350°F/180°C. Grease an 8x8-inch baking pan and line it with parchment paper, leaving a bit of overhang for easy removal later.

Make the Base: In a large bowl, beat softened butter and brown sugar until creamy and smooth. In another bowl mash the ripe bananas until smooth. Combine mashed bananas, vanilla extract, and butter mix. Sift in all-purpose flour, baking powder, and salt, mixing until just incorporated. Fold in the chopped dark chocolate and walnuts. The dough will be soft and slightly sticky. Transfer 1/4th part of the dough into another bowl. Cover and refrigerate till further use.

First Bake: Spread the rest of the dough evenly into the prepared baking pan. Bake in the preheated oven for 10-12 minutes, or until the edges start to set but the center is still slightly soft.

Add the Toppings: Remove the pan from the oven. Sprinkle chocolate and drizzle the caramel sauce over the partially baked base, making sure to cover it evenly. Drop chunks of the refrigerated dough over the base randomly. No need to be thorough.

Final Bake: Return the pan to the oven and bake for an additional 15-18 minutes, or until the caramel is bubbling and the chocolate is melted.

Cool & Slice: Once baked, let the bars cool completely in the pan before slicing.