Preheat your oven to 400°F. Lightly grease the cups of a muffin pan or fill with 12 non-stick liners, like reusable silicone muffin liners
In a large bowl, mix together all of the dry ingredients and set aside.
In a medium bowl or stand mixer, mix together mashed banana with all of the wet ingredients. Slowly add the dry ingredients to the wet ingredients and mix until the batter is just starting to come together. There will be lumps, so be careful not to over-mix. Add in any desired optional nuts or chocolate and give the batter another few stirs to incorporate the add-ins.
Using a cookie scoop or spoon, divide the batter evenly among the muffin pan. Bake the muffins for 22 to 26 minutes or until the muffins have risen and are golden brown on the edges. To double-check, insert a toothpick into the center of a muffin and if it comes out clean the muffins are done.
If you make these into mini muffins, decrease the bake time to about 10 minutes, or until the tops are golden and the centers are fully cooked.
Let cool for 5 minutes in the muffin pan, then remove the muffins to fully cool on a wire rack.
The muffins can be stored in an airtight container at room temperature for 4 days, in the fridge for 3 days, or in the freezer for up to 1 month.