Preheat Oven: Preheat your oven to 350°F (175°C). Line your jumbo muffin pan with jumbo liners.

Prepare Wet Ingredients: In a large mixing bowl, mash the 4 ripe bananas until smooth. Add the dark brown sugar, white sugar, melted unsalted butter, eggs, vanilla extract, and sour cream (or yogurt). Stir everything together until well combined.

Combine Dry Ingredients: In another bowl, whisk together the all-purpose flour, cinnamon, baking powder, and salt.

Mix Wet and Dry Ingredients: Gradually add the dry ingredients to the wet mixture, stirring gently until just combined. Be careful not to overmix, as this can result in dense muffins.

Scoop and Fill: Using a spoon or ice cream scoop, divide the muffin batter evenly into the muffin liners. Fill each liner about ¾ of the way full.

Add Toppings: Sprinkle chopped pecans and a light dusting of coarse sugar on top of each muffin to give them a nice crunch and shine.

Bake: Bake in the preheated oven for 23-25 minutes, or until a toothpick inserted into the center comes out clean.

Cool and Serve: Allow the muffins to cool in the pan for about 5 minutes, then transfer them to a wire rack to cool completely.