Preparation

• Preheat the oven to 375℉. Line a 12-cup muffin pan with paper muffin liners or lightly spray with cooking spray. Set the muffin tin aside.
• In a large mixing bowl, whisk together the all-purpose flour, baking powder, salt, and baking soda until blended.
• In a separate small bowl, whisk together the granulated sugar, sour cream, melted butter, fresh lemon juice, lemon zest, and vanilla extract until mixed thoroughly.
• Add the eggs, one at a time, whisking until the wet ingredients are blended and smooth.
• Gradually fold the wet ingredients into the dry ingredients using a wooden spoon or rubber spatula, and mix just until combined and no flour streaks remain in the batter. Do not overmix.
• Gently fold in the fresh blueberries. Be careful not to burst open the blueberries. Let the muffin batter sit while you prepare the streusel topping.
• In a small bowl, combine the melted butter, granulated sugar, lemon juice, and lemon zest until mixed. Slowly add in the flour, 1-2 tablespoons at a time, and mix gently with a fork until the mixture forms coarse crumbs.
• Fill each muffin cup about ¾ full with muffin batter. Sprinkle about 2 teaspoons of the prepared crumb topping evenly over the top of each muffin.
• Bake for 20-22 minutes or until a toothpick inserted into the center comes out clean. Let the muffins cool in the muffin pan for 10 minutes, then transfer the muffins to a wire rack to cool completely to room temperature (about 20 minutes).
• Once the muffins are cool, whisk together the powdered sugar and fresh lemon juice until smooth. Drizzle the lemon glaze over the top of the muffins. Enjoy!