Preheat oven to 350 F
In a large bowl combine flours, cornstarch, baking powder, baking soda, salt and ground cinnamon. Whisk.
In a different bowl add in sugar, banana and canola oil until smooth. Add in eggs and vanilla, beating well until completely combined, you can use a mixer or do this by hand.
Slowly add in flour mixture from the first bowl then milk and mix until everything is combined.
Line 18 tin muffin tray with either cup liners or cooking spray. Evenly distribute batter into all 18 cups and bake for 20 minutes or until a wooden pick can be inserted into the center and comes out clean. Mine took around 24 minutes but each oven is different so be sure to check around 20 min to make sure they don't overcook.
While they are cooking prepare the frosting. Heat butter in a small saucepan until melted then cook on medium for about 2-3 minutes or until browned - making sure to stir constantly. Remove from heat and cool for 4 minutes. Place butter in a mixing bowl and add the rest of the ingredients. Mix on low or by hand until smooth. Add in more powdered sugar if frosting is too liquid or more milk if frosting is too thick.
Take muffins out of the oven and cool on a cooling rack for about 10 minutes or until they are no longer hot.
Top with frosting and peanut or toffee brickle, ENJOY :)