Preheat the oven to 350ºF.
Sift together the dry ingredients (flour, baking powder, salt, and cinnamon), add the brown sugar and mix well to make sure there are no lumps.
Fold in the wet ingredients (milk, vanilla, coconut oil, and mashed bananas) and mix until just combined, making sure to not overmix.
Pour batter into the wells of a greased donut pan. Bake 14-15 minutes until golden brown.
Let cool completely before decorating.