Grease a 9×5” loaf pan with butter. Set aside.

In a large bowl, whisk together the flour, baking soda, baking powder, salt, cinnamon, and nutmeg. Set aside.

In the bowl of a stand mixer with the whisk attachment, blend the butter, brown sugar, and Stevia together on medium-high speed until smooth and creamy (push down the sides with a spatula as needed). Lower the speed to medium and add the eggs, one at a time, until fully blended. Add in the yogurt and vanilla extract. Add the bananas, one at a time, breaking them up into chunks before adding them to the bowl. Continue to whisk until the bananas have brown up and blended in.

Continue to mix on medium and carefully pour in the flour mixture. Whisk until just blended. Turn off the mixer and add the walnuts. Using a spatula, fold the nuts into the mix. Pour the batter into the greased loaf pan.

Set the oven rack to the bottom third of the oven and place the loaf into a cold oven. Turn the oven on to 350°F. Once the oven comes up to temperature, bake for an additional 60 minutes, or until a toothpick inserted in the center comes out cleanly. NOTE: check the loaf about halfway through; if nicely browned, cover with aluminum foil to prevent overcooking of the crust. Remove and set the loaf pan on a rack to cool. Turn over and the bread should slide out smoothly. Place in a ziplock bag and store in the refrigerator, or wrap tightly in plastic wrap and place in a freezer bag to store in the freezer.