Prep the pan. Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with parchment liners or lightly grease each cup.
Mash the bananas. In a large bowl, mash bananas until mostly smooth with a few small lumps for texture.
Whisk in wet ingredients. Add eggs, Greek yogurt, maple syrup, melted coconut oil, and vanilla.
Whisk until well combined and glossy.
Combine dry ingredients. In a separate bowl, stir together the white whole wheat flour, oat flour, protein powder, baking powder, baking soda, and salt. Break up any clumps in the protein powder.
Bring it together. Add the dry ingredients to the wet. Gently fold with a spatula until just combined.
Do not overmix or the muffins will be dense.
Add the coconut. Fold in the shredded coconut and any optional mix-ins. The batter will be thick and scoopable.
Fill the cups. Divide the batter evenly among the muffin cups. For a bakery-style dome, fill nearly to the top.
Sprinkle extra coconut on top if you like.
Bake. Bake for 16–20 minutes, or until the tops are set and a toothpick 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. This helps the texture set and keeps the liners from sticking.