1. Preheat your oven to 425°F (220°C). Line a standard 12-cup muffin pan with paper liners.

2. Gently melt the unsalted butter and let it cool until it’s just barely warm (around 90°F). Crack your large eggs into a small bowl and set them aside to come closer to room temperature.

3. In a medium-sized bowl, whisk together the all-purpose flour, baking powder, baking soda, and kosher salt for about 30 seconds.

4. Place the granulated sugar in a large mixing bowl. Grate 2 tablespoons of lemon zest directly over the sugar and use your fingers to rub the lemon zest into the sugar. Juice the lemons to get 3 tablespoons of fresh lemon juice.

5. Add the room temperature eggs to your lemon-scented sugar mixture and whisk vigorously for about 1 minute until light and creamy. Whisk in the cool, melted butter. Finally, gently whisk in the room temperature sour cream, the fresh lemon juice, and the pure vanilla extract. Let this vibrant wet batter rest for 5 minutes.

6. Add half of the whisked dry flour mixture to your wet ingredients. Using a spatula, fold it gently until just combined. Then, add the remaining flour mixture and continue to fold gently until no streaks of flour remain. Let the batter rest for 10 minutes.

7. While the batter rests, take your frozen blueberries and place them in a small bowl. Toss them with 1 tablespoon of flour until all the berries are lightly coated. Add the coated berries and any leftover flour to the lemon muffin batter. Gently fold in the blueberries until they are well distributed.

8. Divide the batter evenly among the 12 muffin cups (about 80 grams per muffin). Sprinkle about 1/2 teaspoon of sanding sugar over the top of each muffin.

9. Bake the muffins at 425°F (220°C) for 5 minutes. Without opening the oven door, reduce the oven temperature to 350°F (180°C). Continue baking for another 20-22 minutes, until the tops are golden brown and a thermometer inserted into the center of a muffin registers about 200°F (93°C).

10. Allow the muffins to cool in the pan for 5 minutes. Then, carefully transfer them to a wire cooling rack to cool completely.

11. (Optional Glaze) Sift the powdered sugar into a small bowl. Add 3 teaspoons of fresh lemon juice and stir until it forms a very thick paste. Add the remaining lemon juice 1/2 teaspoon at a time, stirring well after each addition, until your desired drizzle consistency is reached.

12. (Optional Glaze) Once the muffins are completely cool, drizzle the bright, tangy lemon glaze generously over each one.

13. (Storage) Store muffins at room temperature in an airtight container for up to 1 day, or in the refrigerator for up to 5 days.

14. (Freezing) To freeze, wrap each muffin tightly in plastic wrap once cool. Place wrapped muffins in a freezer-safe bag/container and freeze for up to 2 months.

15. (Serving from Frozen) To serve from frozen, thaw overnight in the refrigerator or for about an hour at room temperature. Warm in microwave for a few seconds or in the oven for 5 minutes at 350°F (180°C).