Melt the butter and mash the banana. Combine to a bowl with egg and vanilla extract.
2
To a bowl, combine brown sugar, flour and baking soda.
3
Mix the wet with the dry.
4
Fold in the blueberries gently. Line a muffin tray with muffin liners, and set the oven to 175 C. Bake for 15–25 minutes. Check with a small toothpick whether they are done. If the dough is wet and sticks to the toothpick, give it a few more minutes
5
Let them rest on a wire rack for 20 minutes before serving.
