Preheat the oven to 400 degrees. Coat a muffin tray with cooking spray.
Prepare the the banana bread muffins by whisking together the flour, sugar, baking soda, baking powder, cinnamon and salt together in a large bowl until well combined.
In a separate bowl whisk together the well mashed banana, sour cream, eggs, melted butter and vanilla until very well combined.
Lightly fold the banana mixture into the flour mixture with a rubber spatula until just combined.
Pour the batter equally into the muffin pan filling them to the top.
Sprinkle some coarse turbinado sugar on top of each muffin.
Place into the oven and bake for 5 minutes. Reduce the heat to 350 degrees and continue to cook for 13-15 minutes, or until a tester inserted in the center comes out clean.
Remove from the oven and cool in the pan for a few minutes before putting them on a wire rack to finish cooling. Serve and enjoy. Side Note: Starting the baking at a higher temperature then reducing it helps make the high muffin dome.