Place 1 tablespoon of butter in a ramekin or large coffee mug and melt for 30 seconds in the microwave. Add in coconut sugar mashed banana, vanilla, orange zest, brown rice flour, baking powder and raspberries and stir to combine completely.
In a separate bowl combine topping ingredients except raspberries and combine with your hands, squeezing the butter into the other ingredients until it is combined and crumbly. Pour topping on the cake batter and then top with raspberries.
Microwave for 2 minutes on high. Let cool for a few minutes and enjoy!