Prep the oven and pan: Preheat oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or grease lightly.
Mash the bananas: In a large bowl, mash bananas until mostly smooth with a few small lumps for texture.
Whisk in wet ingredients: Add honey or maple syrup, oil (or Greek yogurt), eggs, and vanilla.
Whisk until well combined and glossy.
Mix dry ingredients: In a separate bowl, whisk flour, baking soda, cinnamon, nutmeg (if using), and salt.
Combine wet and dry: Add dry ingredients to the banana mixture. Pour in the milk. Stir gently with a spatula until just combined. Do not overmix; a few streaks of flour are okay.
Fold in extras: If using nuts, chocolate chips, or berries, fold them in gently.
Fill the cups: Divide batter evenly among the muffin cups, filling each about 3/4 full.
Sprinkle oats or turbinado sugar on top if you like.
Bake: Bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs.
Cool: Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. Cooling helps set the crumb and keeps them tender.