Banana Nutella Muffins

Before getting started, preheat your oven to 350ºF. Then line your muffin tin cups with muffin liners.
In a medium mixing bowl, use a fork to mash up the overripe bananas, setting them aside for later.
In a large bowl, cream together the butter, cream, brown sugar and cane sugar 'til well combined. I use my electric hand mixer or electric stand mixer for this step.
Whisk in the eggs one at a time 'til well combined. Blend in the sour cream.
Then add the mashed bananas and vanilla extract, whisking everything together.
In a separate medium mixing bowl, whisk together the flour, baking soda, baking powder and salt.
Add the flour mixture to the muffin batter, mixing with a spatula just until incorporated.*
Pour the batter into the muffin tins that you lined in the first step, 'til each cup is about 2/3 full.
Warm the Nutella in a microwave-safe bowl in the microwave for 15-20 seconds in order to soften it for easier swirling.
Add a dollop of Nutella to the top of each muffin, and use a toothpick to sort of swirl it in circles into the batter.
Bake your banana Nutella muffins at 350ºF for about 15-20 minutes. You can tell that they're done baking when a toothpick inserted into the center comes out clean.
Remove your muffins from the oven, serve and enjoy while warm!