Heat the oven to 400°F. Line a 12-cup muffin pan with paper liners and set aside.
In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and espresso powder. Remove 2 tablespoons of this mixture to a small bowl for later tossing with the chips.
In a separate bowl, whisk the eggs, brown sugar, and granulated sugar vigorously for about 1 minute until slightly thickened and glossy. Slowly whisk in the oil and the cooled melted butter until the mixture looks smooth and emulsified. Stir in the milk and vanilla, then fold in the mashed bananas.
Toss the mini chocolate chips with the reserved flour mixture to lightly coat. Add the wet mixture to the dry ingredients and fold gently with a spatula until a few flour streaks remain. Fold in the floured chips just until evenly distributed; avoid overmixing.
Let the batter rest for 10 minutes on the counter to hydrate the flour and encourage taller domes.
Portion the batter with a heaping 1/4-cup scoop into the liners, filling nearly to the top. Sprinkle each with a pinch of extra mini chips and a light dusting of turbinado sugar if using.
Bake at 400°F for 8 minutes, then (without opening the oven) reduce the temperature to 350°F and continue baking for 10 to 12 minutes, until the tops are golden and a toothpick inserted in the center comes out with a few moist crumbs.
Cool in the pan for 5 to 10 minutes, then transfer muffins to a wire rack to finish cooling. Enjoy warm or at room temperature.