Preheat oven to 375 degrees F. Line a muffin pan with muffin liners.

Caramelize bananas. Slice bananas into 1-inch thick slices. Melt 2 tablespoons butter in a large saute pan over medium heat. Add sliced bananas and cook until browned. Flip and cook until browned and caramelized. Remove from heat and transfer bananas and any remaining melted butter into a heat safe bowl. Mash bananas and let cool.

Make peanut butter streusel. Combine melted butter with peanut butter in a medium bowl, mixing until combined. Add flour, brown sugar, and cinnamon, and stir until well combined. The streusel will almost be like a paste.

Make muffin batter. Combine both flours, baking powder, salt, and cinnamon in a medium bowl.

Combine softened butter and brown sugar in the bowl of a stand mixer and beat for 4-5 minutes or until creamy and fluffy. Add buttermilk, yogurt, egg, vanilla, and mashed bananas and mix until well combined.