Preheat oven to 375°F. Line a muffin pan. My favorite muffin liners are linked in the blog post above! If adding walnuts or pecans, toast them in the oven while it preheats for 5 to 8 minutes.
Whisk all the wet ingredients together in a medium bowl (2 ripe bananas smashed, 2 eggs, 1/2 cup avocado oil, 1/2 cup pure maple syrup, 1/2 cup sourdough discard, 1 teaspoon vanilla extract).
Mix all the dry ingredients together in a small bowl (1 1/4 cups flour, 1/4 cup ground flax meal or flour, 1/2 teaspoon fine sea salt, 1/2 teaspoon baking powder, 1 teaspoon baking soda, 1/2 teaspoon cinnamon).
Pour the dry ingredients into the wet mixture, gently mix to combine. When only a few dry streaks of flour remain, stir in chocolate chips or nuts if using.
Spoon the batter into the prepared muffin tin, filling each about 3/4th of the way full.
Bake at 375°F for 18 to 20 minutes, or until a toothpick inserted into the center comes out clean.
Enjoy!