Preheat oven to 350ºF. Fill a muffin pan with paper liners and set aside.
Prepare the muffin base: In a medium bowl, mix flour, sugar, baking soda, and salt. Set aside.In the bowl of a mixer fitted with the paddle attachment, mash the bananas. Add eggs and beat to combine. Add maple syrup and almond milk. Add flour mixture to the banana mixture, beating to combine. Add oil and mix again. If making the base muffin recipe, add chocolate chips, if using, and skip to step 6.
If making the chocolate banana muffins, add the cocoa powder, chocolate chips, vanilla extract, and almond milk, mixing until just combined. If making the banana nut muffins, add the walnuts, cinnamon, and vanilla extract, mixing until just combined. Fill muffin cups about ¾ of the way. Bake 18–22 minutes or until a toothpick inserted in the center comes out clean.
