Preheat the oven to 375℉ and prepare a 12 slot muffin tin with paper liners or baking spray.
Mash bananas into a puree (measure to be accurate).
Transfer the mashed bananas to a mixing bowl, and combine with brown sugar, milk, sour cream (or plain greek yogurt) egg, melted butter, and vanilla extract. Whisk until everything mixed together well.
Add in the shredded carrots and spices, and mix well.
Add in the flour, and baking powder on top of the wet ingredients, and mix until just combined. Then gently stir in the chopped pecans if you wish to add nuts.
Scoop in equal portions into a 12 slot muffin tin, filling each slot about ¾ full.
Place a pecan half on each muffin. Bake for 16-18 minutes on a middle shelf, until an inserted toothpick comes out clean.
Optional but delicious: make a light icing by combining powdered sugar, vanilla, and milk and drizzling over the muffins after cooling for 10-15 minutes. Enjoy warm!