Preheat oven to 425 degrees F. Lightly coat a muffin tin with baking spray or line with paper cups. (This recipe usually yields 12 regular-sized muffins.)
Place peeled bananas in a large bowl or in your stand mixer. Beat or mix with a fork until very well mashed, then add the milk, brown sugar, honey or syrup, oil, egg, and vanilla.
2 large very ripe bananas, 2/3 cup milk, 1/3 cup light brown sugar, 1/4 cup honey or maple syrup, 1/4 cup vegetable or coconut oil, 1 large egg, 1 teaspoon vanilla extract
Mix into an even batter, then sprinkle flour, cinnamon, baking powder, baking soda, and salt on top. Stir or beat on low speed, again until evenly combined. Gently fold in the blueberries.
2 cups all-purpose or white whole wheat flour, 1 teaspoon ground cinnamon, 1 teaspoon baking powder, 1 teaspoon baking soda, 1/4 teaspoon kosher salt, 1 and 1/4 cups fresh blueberries
Divide batter evenly among muffin cups, filling each to the top. (A large cookie dough scoop makes this so easy.) If desired, press extra blueberries and sprinkle a bit of coarse sugar on top of each muffin.
coarse sugar
Bake at 425 degrees for 5 minutes, then, without opening the oven door, reduce the temperature to 350 degrees and bake for another 15-18 minutes. When done, the muffins will be golden on top and a toothpick inserted into the centers will come out clean or with moist crumbs, but no large streaks of batter.
Let cool for about 10 minutes in the pan, then remove to a wire rack to cool completely.