2 tbsp butter, melted
½ medium banana, mashed
1 egg
2 tbsp brown sugar
¼ tsp vanilla extract (optional)
3 tablespoons all-purpose flour
¼ tsp baking powder
pinch of ground cinnamon (optional)
1 tbsp chopped walnuts or pecans
Find it online: https://misswish.com/banana-mug-cake