Preheat the oven to 375 degrees. Coat a muffin tray with cooking spray.
Combine the flour, baking powder, salt, cinnamon, and 1 tablespoon of lemon zest in a small bowl.
Using a hand mixer, beat the bananas, eggs, brown sugar, melted butter, lemon juice, and vanilla until well blended. Stir in the dry ingredients until just combined then carefully add 1 cup of blueberries and gently mix.
Scoop the batter evenly into the muffin tray.
Sprinkle the remaining blueberries evenly over the tops of each muffin, making sure to push them down a bit.
Combine the sugar and remaining tablespoon of lemon zest and sprinkle evenly on the top of each muffin.
Place into the oven and bake for 25-27 minutes or until a tester inserted in the center comes out clean. Remove from oven and cool on a wire rack for a few minutes. Enjoy.