Steps
1. Preheat oven to 180°C (350°F). Grease a small ramekin with butter.
2. Melt butter and chocolate together in a microwave or double boiler; set aside to cool slightly.
3. In a bowl, mash the banana until smooth.
4. Add the egg and sugar to the mashed banana and whisk until combined.
5. Stir in the melted chocolate and butter mixture.
6. Sift in the flour, baking powder, and salt, then gently fold into the wet ingredients.
7. Pour the batter into the prepared ramekin.
8. Bake for 15-18 minutes or until a toothpick inserted comes out clean.
9. Let cool for a few minutes before serving warm.