Preheat and prep. Preheat your oven to 220°C (425°F) and line a 12-hole muffin pan with paper liners.
Whisk the eggs and sugars. In a large bowl, whisk together the eggs, brown sugar, and granulated sugar until smooth.
Add the wet ingredients. Add the mashed banana, oil, Greek yogurt, milk, and vanilla. Mix until well combined and smooth.
Fold in the dry ingredients. Add the flour, baking powder, baking soda, and salt directly into the bowl. Mix gently just until the flour disappears. Overmixing here is the number one way to end up with dense muffins, so stop as soon as you don't see dry flour.
Add ins. Gently fold in the chocolate chips or any add ins you’d like.
Fill the muffin cups. Divide the batter evenly among the 12 liners, filling almost to the top.
Bake in two stages. Bake for 5 minutes at 220°C (425°F), then lower the oven to 180°C (350°F) without opening the door and bake for another 13 to 15 minutes more, about 18-20 minutes in total.
Check for doneness. A toothpick inserted in the center should come out clean or with just a few moist crumbs. Enjoy!