Step 1: Preheat your oven to 400°F (200°C). Line a 12-cup muffin pan with paper liners or grease it thoroughly with non-stick spray. This high initial temperature helps create those lovely domed tops on your muffins.
Step 2: In a large bowl, whisk together the all-purpose flour, granulated sugar, baking powder, and salt. Make sure these dry ingredients are well combined to ensure even leavening throughout your muffins.
Step 3: In a separate medium bowl, whisk together the melted unsalted butter, buttermilk, egg, vanilla extract, and lemon zest. Whisk until well combined. The lemon zest should be fragrant and evenly distributed.
Step 4: Pour the wet ingredients into the dry ingredients. Using a rubber spatula, gently fold until just combined. The key here is not to overmix! Overmixing will develop the gluten in the flour too much, resulting in tough, chewy muffins. A few lumps are perfectly fine.
Step 5: Gently fold in the fresh blueberries. Be very careful not to mash them. You want them to remain intact for those juicy bursts of flavor.
Step 6: Divide the batter evenly among the 12 muffin cups. Fill each cup about two-thirds full. For an extra touch of sweetness and sparkle, you can sprinkle a little extra granulated sugar on top of each muffin before baking.
Step 7: Bake for 5 minutes at 400°F (200°C), then reduce the oven temperature to 375°F (190°C) and continue to bake for another 15-18 minutes, or until a wooden skewer inserted into the center of a muffin comes out clean. The initial high heat creates a beautiful rise, giving you those classic muffin tops.
Step 8: Remove the muffin pan from the oven and let the muffins cool in the pan for 5 minutes before transferring them to a wire rack to cool completely. Allowing them to cool slightly in the pan prevents them from sticking and helps them hold their shape.