Use electric mixer to combine 1/2 cup softened butter with coconut sugar until creamy. Add vanilla and eggs and beat until combined. Add the banana and mis again until combined.
Combine the dry ingredients: flour, salt, baking powder, baking soda in a bowl. Add the dry ingredients and buttermilk in thirds alternating between the dry ingredients and buttermilk while continuously mixing until fully combined.
Line a cupcake it with cupcake liners. Fill each with approximately 3 tbsp of batter. I used my 1.5 tbsp cookie scoop and put two scoops per cupcake.
Bake for 18-23 minutes or until a toothpick inserted into the center of a cupcake comes out clean. Allow to cool fully before frosting.
Making the frosting
Combine peanut butter and butter in a mixing bowl and use an electric mixer on medium speed to beat until smooth. Add powdered sugar and continue to beat on medium for about one minute. Add cinnamon, milk and pinch of salt and continue beating until smooth.
Frost each cupcake with a generous amount of frosting using an off-set spatula for precision.