Preheat your oven to 350°F (175°C) and line a small baking dish with parchment paper.
In a mixing bowl, mash half of a ripe banana until smooth.
Add 2.5 tbsp unsweetened cocoa powder, 2.5 tbsp natural unsweetened peanut butter, and 1 tbsp of your preferred sweetener (optional). Mix until well combined.
Spread the mixture evenly in the prepared baking dish.
Top with 2-3 tbsp of sugar-free chocolate chips if desired.
Bake for 25 minutes or until the brownie is set and firm in the middle.
Remove from the oven, let it cool for a few minutes, and then cut into 2 servings. Enjoy!
