Turn oven on to 400 degrees
Combine in a medium bowl flour, flaxseed meal, baking powder, baking soda, salt, and cinnamon. Mix well and set aside.
In a large bowl, using a hand mixer, mix together bananas, greek yogurt, eggs, and sugars. Slowly mix in the butter until combined.
Slowly stir in the flour mixture into the banana mixture until just combined. Don’t over mix.
Take half of the batter and place into another bowl (I quickly washed out and used the dry ingredient bowl). Stir the nutella into one of the batters.
Place about 2 tablespoons of each batter (start with the plain banana batter and end with nutella batter) into each muffin cup sprayed with cooking spray. Using a butter knife gently swirl the batters together.
Bake for 14-16 minutes or until toothpick comes out of a muffin clean. Let cool in muffin pan for about 5 minutes then place muffins on baking rack to finish cooling. Enjoy warm or at room temperature.