Start by preheating the oven to 350 degrees Fahrenheit (180 C). In a large bowl, begin by mashing the peeled bananas with a fork. Some small chunks can remain, but try to mash it enough for an even texture. Stir in melted butter, olive oil, applesauce, spices, sugar, and vanilla until fully combined. Then mix in one egg.
On top of the wet ingredients, add flour, baking powder, salt, and baking soda. Then gently stir that into the wet ingredients. A dough mixer can make this very easy!
Fill a muffin tin with liners and spoon the muffin mixture into each, filling about 3/4 full. This should create 11-12 muffins. Sprinkle a small pinch of oats on top, if desired.
Bake for 15-17 minutes, till just light brown on top and set. The muffins may appear a little underdone, but will continue cooking after you remove them from the oven. This will retain a moist texture. Allow the muffins to cool at least 5 minutes before removing them from the pan and serving.
Notes
For an accurate flour measurement, scoop the flour into a measuring cup with a spoon, then level with a knife. Do not directly scoop the measuring cup into the flour.
Because of the low sugar added to this recipe, make sure the bananas have browned at least enough to be speckled and are not a green color.
For babies and younger kids - Just omit the added sugar! You can also substitute maple syrup. Sugar creates softness and moisture in a muffin recipe, so we add a little bit here for texture purposes and so they will keep well without drying out. I find babies aren't that picky with this recipe!