Preheat the oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line with parchment paper.
In a large mixing bowl, mash the bananas until smooth. Add the eggs, melted butter, brown sugar, vanilla extract, and Greek yogurt, and whisk until well combined.
In a separate bowl, sift together the flour, baking soda, salt, cinnamon, and nutmeg. Gradually fold the dry ingredients into the wet ingredients until just combined. Avoid overmixing.
If desired, fold in the walnuts or chocolate chips.
Pour the batter into the prepared loaf pan and spread evenly.
Bake in the preheated oven for 55-65 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bread to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
