PREP: Preheat the oven to 350 degrees F. Spray all 12 cavities of a muffin tin with cooking spray and lightly flour. Shake out any excess flour and set aside
WET INGREDIENTS: Mash 2 very ripe bananas to get 1 level cup of mashed banana (See Note 2). Mash to get rid of any/all chunks. Add to a large bowl. Add in the large egg, 1/2 cup melted (and cooled; don't add hot oil) coconut oil, 1/2 cup honey, 1/4 cup Greek yogurt, and 1 and 1/2 teaspoons vanilla extract. Whisk until combined and smooth.
DRY INGREDIENTS: In a separate bowl, add the 1 teaspoon baking soda, 1 teaspoon baking powder, 1 teaspoon cinnamon, and 1/2 teaspoon sea salt to a large bowl. Add in the 1 and 3/4 cup flour (spoon flour into the measuring cup and level the top) and if desired, 1/2 cup nuts or miniature chocolate chips. Stir until combined. Add wet into dry ingredients. Mix until just combined. Do not over-mix; this will cause deflated or dense muffins. Add the batter evenly between the 12 muffin cups; each muffin cavity should be pretty much filled to the top and all batter should be used among the 12 cavities.
CRUMB TOPPING: Combine the 2 tablespoons brown sugar, 2 tablespoons white sugar ,1/4 cup + 2 tablespoons flour, 1/2 teaspoon cinnamon, and 1/8 teaspoon salt. Whisk until combined and then add in the melted (but not hot) butter and stir until crumbs form. Sprinkle this mixture evenly onto the 12 muffins.
BAKE: Bake for 15-18 minutes or until a toothpick when inserted into the center comes out dry or with a few moist crumbs. Remove and allow to cool for 5 minutes before pulling out the muffins and transferring to a cooling rack.