Preheat your oven to 375˚F. Spray your muffin pan with cooking spray, use cupcake liners, or use another preferred non-stick method. Set aside.
In a medium bowl, mix your bananas, sugar, oil, and vanilla extract until combined well.
Add the remaining ingredients (flour, baking soda, cinnamon, nutmeg, and salt) to your wet ingredients and mix until just combined, making sure to scrape the bottom and sides of the bowl.
Divide the batter evenly between the 12 cups in the muffin tin, each one should be 3/4 or almost full.
Bake for 20 minutes or until a toothpick inserted into the center comes out clean and muffins are rounded on top. If the toothpick has wet batter on it, put the muffins back in for 5 minutes at a time, keeping an eye on them.
Remove the muffins from the oven and let them cool in the muffin pan for 5 minutes. Move them to a cooling rack and cool until you're able to handle them with bare hands.