Step 1

Preheat oven to 350F.

Step 2

Whisk milk with lemon juice and set aside.

Step 3

Blend rolled oats into fine oat flour, and then mix the flour with baking powder, baking soda, salt, and cinnamon.

Step 4

Mash bananas in a separate bowl and set aside.

Step 5

Cream together softened butter and coconut sugar with an electric mixer. Mix in eggs, maple syrup, and vanilla extract.

Step 6

Fold in 1/4 of the dry ingredients, mix them until combined, and then add 1/4 of sour milk then mix again. Repeat alternating dry ingredients mix and sour milk until everything is incorporated.

Step 7

Fold in (use a spatula, not the mixer) to mix in the mashed banana. Bake in a parchment paper-lined 9 x 13 glass dish for 45 minutes or until an inserted toothpick comes back clean.

Step 8

Let cool for one hour on a cooling rack before serving. If you want to add frosting, let cool overnight in the fridge, so the frosting doesn't melt when you try to add it. Once you add the frosting, it's ready to serve, best served cold, or at room temperature.