Preheat and Prepare: Preheat your oven to 375°F (190°C). Line a standard 12-cup muffin tin with paper liners or grease it well with non-stick spray.

Combine Wet Ingredients: In a large mixing bowl, add the mashed bananas, eggs, Greek yogurt (or milk), maple syrup, melted coconut oil, and vanilla extract. Whisk everything together until it is well-combined and smooth.

Combine Dry Ingredients: Add the rolled oats, baking powder, baking soda, ground cinnamon, and salt directly to the bowl with the wet ingredients.

Mix the Batter: Using a spatula, gently fold the dry ingredients into the wet ingredients until just combined. Be careful not to overmix! A few lumps are perfectly fine. Overmixing can lead to dense, tough muffins.

Add Optional Mix-Ins: If you are using chocolate chips, nuts, or berries, gently fold them into the batter now.

Fill the Muffin Tin: Divide the batter evenly among the 12 prepared muffin cups. They should be about three-quarters full.

Bake to Perfection: Place the muffin tin in the preheated oven and bake for 20-24 minutes. The muffins are done when they are golden brown on top and a toothpick inserted into the center of a muffin comes out clean or with a few moist crumbs attached.

Cool and Enjoy: Let the muffins cool in the tin for about 5-10 minutes before transferring them to a wire rack to cool completely. They are delicious warm but will hold together better once they have cooled.