How to cook
Beat the butter and sugar, and eggs, but separately, and then mix them. Add the bananas and lemon juice. Mix the flour, oats, baking powder and salt and quickly add them to the banana mixture.
Chop the walnuts into small pieces and add them. The dough should be slightly thicker than normal cake batter. If desired, add 1-2 tablespoons of flour or yogurt.
Put the dough into greased muffin trays and bake at 392°F (200 °C) about 15-20 minutes.