In a large bowl, whisk the flour, baking powder, baking soda, cinnamon, ground cloves, and salt together until combined. Set aside.
In a medium-sized bowl, whisk the granulated sugar and eggs together for about 30 seconds. Whisk in the sour cream, buttermilk, unsalted butter, vanilla extract, and mashed bananas. Pour the dry ingredients into the wet ingredients, and whisk until combined.
Heat the Nutella in the microwave for about 20 seconds to soften.
Fill muffin tins 3/4 full. Top each muffin with about 1 teaspoon of Nutella and use a toothpick to swirl it into the batter. Top the muffins with the remaining batter and scoop another half teaspoon of Nutella and swirl.
Bake at 400℉ (204℃) for 20-22 minutes or until a toothpick inserted in the center comes out clean. Allow to cool for 15 minutes before serving.