Preheat the oven to 400 degrees. Spray 2 muffin tins with non stick cooking spray and line with 14 muffin liners.

In a large bowl, whisk together the butter, brown sugar, and white sugar until no lumps remain. Stir in the sour cream. Add the eggs, one at a time, whisking well after each addition. Whisk in the vanilla until well combined.

In another bowl, mash the bananas then stir them into the butter mixture.

In a third bowl, whisk together flours, soda, powder, salt, and cinnamon. Gently stir the flour mixture into the banana mixture with a wooden spoon or spatula.

Stir in all but 1/4 cup of the cinnamon chips and the walnuts.

Use a cookie scoop to fill the muffin cups nearly to the top. Sprinkle with reserved cinnamon chips and walnuts.

Place the muffins in the oven and reduce heat to 350. Bake for 20-25 minutes or until toothpick inserted in center comes out clean. Allow to cool in the muffin tin for 5 minutes, then remove and cool completely on a wire rack. Store in an airtight container.