Super Moist Banana Cake How to make a super moist banana butter cake. Here's what you'll need: 3 medium overripe bananas (225g) or 1 cup when mashed 3 large eggs 1 cup brown sugar (200g) or dark brown sugar 1/2 cup butter (115g) 2 tbsp oil (30ml) 1/2 tbsp vanilla extract (8ml) 2 cups cake flour (240g) or 2 cups all purpose flour (250g) 1 tsp baking powder (4g) 1 tsp baking soda (4g) 1 tsp salt (4 g) 3 tbsps milk (45ml) | Savor Easy