Preheat the oven to 375°F (190°C) and line a muffin tin with paper liners or lightly grease the cups.
In a large bowl, mash one ripe Banana until mostly smooth; stir in about 1/3–1/2 cup of Peanut Butter until well combined to create a creamy batter base.
Crack and whisk one Egg in a small bowl, then mix it into the banana–peanut butter mixture until smooth and uniform.
Gently fold in about 1 cup of fresh Blueberries, taking care not to crush them so they keep their juicy pockets in the muffins.
Sprinkle in about 1–2 teaspoons of Baking Powder and fold just until incorporated to help the muffins rise; avoid overmixing to keep the texture tender.
Spoon the batter evenly into the prepared muffin tin, filling each cup about two-thirds full.
Bake for 15–20 minutes, or until the tops are golden and a toothpick inserted into the center comes out clean or with a few moist crumbs.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool slightly before serving. Enjoy warm or at room temperature.
