Prepare the Baking Pan

• Preheat the oven to 350°F (175°C).
• Line an 8 × 8-inch baking pan with parchment paper, leaving some overhang on the sides for easy removal.
• Lightly grease the parchment paper.

Mix the Wet Ingredients

• In a large mixing bowl, whisk together the melted butter and granulated sugar until smooth.
• Add the mashed banana and mix until combined.
• Beat in the eggs and vanilla extract until the mixture looks glossy and well blended.

Combine the Dry Ingredients

• In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt.
• Gradually fold the dry ingredients into the wet mixture.
• Mix gently just until no dry streaks remain. Avoid overmixing to keep the brownies tender.

Add the Chocolate

• Fold in the semi-sweet chocolate chips and chopped walnuts, if using.
• Spread the batter evenly into the prepared baking pan.
• Sprinkle a few extra chocolate chips over the top if desired.

Bake the Brownies

• Bake for 25–30 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs.
• Avoid waiting until the toothpick comes out completely clean, as this can make the brownies dry.
• Remove from the oven and allow the brownies to cool completely in the pan.

Prepare the Chocolate Topping

• Place the chocolate chips and heavy cream in a microwave-safe bowl.
• Heat in 20-second intervals, stirring between each interval, until melted and smooth.
• Spread the chocolate topping evenly over the cooled brownies.
• Sprinkle with chopped walnuts or extra chocolate chunks if desired.

Slice and Serve

• Refrigerate the brownies for 15–20 minutes to help the topping set.
• Lift them out of the pan using the parchment paper and cut into squares with a sharp knife.
• Serve at room temperature for soft, fudgy banana brownies with rich chocolate flavor.