Heat the oven
Preheat oven to 350°F. Grease a 9 x 5-inch loaf pan with nonstick cooking spray.
Beat the wet ingredients
Use a hand mixer or standing mixer with a whisk attachment to cream the butter with the brown sugar until light and fluffy. Add the JUST Egg and vanilla extract and beat until incorporated, scraping down bowl as needed. Mash the banana thoroughly, then mix in the mashed banana and yogurt in as well.
Note: We like to use coconut yogurt. If you don’t have yogurt, mix 3 tablespoons of milk (any kind) with ¼ teaspoon of apple cider vinegar. Let it stand for a minute or two before adding to the batter.
Whisk the dry ingredients
In a separate bowl, whisk together the flour, baking powder, baking soda and salt.
Mix everything together
Add the dry ingredients to the wet ingredients and stir until just combined. Do not overmix. If using, fold in the walnuts or chocolate chips.
Bake for 1 hour
Pour the batter into the prepared loaf pan and bake at 350°F for about 1 hour, until a skewer or toothpick inserted in the middle comes out clean, with no gooey batter on it. Depending on your oven, it may need 10-15 more minutes. Let it rest for 10-15 minutes, then remove from the loaf pan and cool completely on a wire rack before slicing.