Preheat the oven to 350 degrees F. Line a muffin pan with paper liners and set aside.
In a medium bowl, whisk together flour, baking powder, baking soda, salt, and cinnamon. Set aside.
Peel the bananas and mash with a fork until smooth. Place the mashed bananas in the bowl of a stand mixer. Add the brown sugar, honey, coconut oil, egg, vanilla and beat until combined. Add in the peanut butter and beat until smooth. Add the flour mixture and milk alternately, starting and ending with the flour. Mix until just combined. Don't overmix.
Fill muffin liners three-quarters full. Sprinkle with turbinado sugar, if desired. Bake until toothpick inserted into center comes out clean, about 20-22 minutes. Transfer to wire rack to cool. We like to serve the muffins with peanut butter and a drizzle of honey. Store, covered, at room temperature for up to 3 days.
Note-these muffins freeze well. To reheat, place muffin in the microwave for about 30 seconds.