Beat the butter and sugar together in either a standing mixer with the paddle attachment or a handheld mixer on medium speed, or by hand with a whisk and a lot of elbow grease. Beat until light and fluffy.
Add the eggs in one at a time and beat until fully incorporated.
Reduce speed to low and add in bananas, vanilla, and milk.
Mix all dry ingredients together in a separate bowl.
Add the dry ingredients to the wet ingredients and mix on low speed until fully incorporated.
Pour batter into a parchment lined and lightly greased loaf pan. Bake for 45 minutes to 1 hour, until a toothpick comes out clean.
While bread is baking, add the chocolate to a glass bowl. Heat the coconut milk on the stove top and pour over chocolate. Stir well until chocolate is melted and a thick consistency has formed. Drizzle over the bread once it has cooled!
Notes
*I make my own oat flour by pulsing 1 cup rolled oats in a blender. You may sub 2 cups oat flour or 2 cups GF flour (or normal flour, if not sensitive), but consistency will be a little different