Preheat and prep: Heat your oven to 350°F (175°C).
Line a 12-cup muffin pan with paper liners or lightly grease it.
Mash the bananas: In a large bowl, mash the bananas with a fork until mostly smooth. A few small lumps are fine.
Whisk in wet ingredients: Add Greek yogurt, honey or maple syrup, oil, eggs, and vanilla. Whisk until well combined and creamy.
Combine dry ingredients: In a separate bowl, whisk the whole wheat flour, all-purpose flour, baking soda, baking powder, cinnamon, and salt.
Bring it together: Add the dry mixture to the wet ingredients.
Stir gently with a spatula until just combined. Do not overmix. If using add-ins, fold them in now.
Fill the pan: Divide the batter evenly among the muffin cups, filling each about 3/4 full.
Bake: Bake for 16–20 minutes, or until the tops are set and a toothpick inserted in the center comes out with a few moist crumbs but no wet batter.
Cool: Let the muffins cool in the pan for 5 minutes, then transfer them to a wire rack to finish cooling.
This helps prevent soggy bottoms.
Serve: Enjoy warm or at room temperature. A swipe of peanut butter or almond butter is a nice touch.