Preheat the oven to 375°F. Line a standard muffin tin with paper liners or grease the cups with non-stick cooking spray.
In a large mixing bowl, combine the flour, granulated sugar, baking powder, baking soda, salt, and lemon zest. Stir well to combine.
In another bowl, whisk together the melted butter, eggs, sour cream, milk, and vanilla extract.
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix; a few lumps are okay.
Gently fold in the fresh blueberries. Toss the blueberries in a little flour before adding them to the batter to prevent them from sinking to the bottom of the muffins.
Divide the batter evenly among the muffin cups, filling each about 2/3 full.
Bake in the preheated oven for 20-22 minutes or until the muffins are golden brown and a toothpick inserted into the center comes out clean.
Once the muffins are done baking, let them cool in the muffin tin for a few minutes, then transfer them to a wire rack to cool completely.
Once the muffins are cooled completely, prepare the lemon glaze. In a small bowl, whisk together the powdered sugar, fresh lemon juice, lemon extract, and lemon zest until you achieve a smooth, pourable consistency. Change the amount of lemon juice to adjust the desired thickness. If it becomes too thin, add more powdered sugar.
Once the muffins have cooled, drizzle the lemon glaze over the top of each muffin.
Allow the glaze to set for several minutes before serving.