In a large mixing bowl, mash the bananas with a fork until mostly smooth. (It’s ok if there are still some lumps). Whisk in the yogurt/sour cream, oil, vanilla extract, eggs and both sugars until smooth
Stir the flour, baking powder, baking soda, salt and cinnamon directly into the wet mixture. Fold the dry ingredients into the wet ingredients with a spatula until just combined. Gently fold in the blueberries
Fill muffin tins all the way to the top for large bakery-style muffins, or ¾ of the way for smaller muffins. Optional: top each muffin with a few more blueberries and a sprinkle of coarse sugar
For large muffins: Bake for 22-24 minutes or until a toothpick inserted into the center comes out clean
For smaller muffins: Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean
