Make the Batter

1. Preheat the oven to 220℃ (425℉) and line the muffin pans with 12 tulip muffin cases.
2. Toss the blueberries with 1–2 tablespoons of flour. This prevents them from sinking to the bottom.
3. In a separate bowl, whisk together the remaining flour, baking powder, and salt. Set aside.
4. Zest and juice the lemon.
5. In a large mixing bowl, add the zest to the sugar and rub together for 1–2 minutes. This helps the sugar absorb the oils from the zest, enhancing the lemon flavor.
6. Cream the butter with the lemon-infused sugar on medium speed until pale and fluffy. Scrape the bowl if needed.
7. Beat in the eggs until combined.
8.  Add the lemon juice and lemon extract, mixing briefly.
9. Add the dry ingredient mixture and milk alternately, starting and ending with the dry mix. Mix each addition just until combined.
10. Gently fold in the flour-coated blueberries. If using frozen blueberries, the batter may thicken slightly.

Bake and Cool the Muffins

1. Divide the batter evenly among the muffin cups.
2. Bake in a preheated oven at 220°C  (425℉) for 5 minutes, then reduce the heat to 180°C  (350℉) and bake for another 13–15 minutes, or until a skewer inserted comes out clean.
3. Let the muffins cool slightly in the pan, then transfer to a wire rack to avoid soggy bottoms.

Make the Glaze

1. In a small bowl, mix icing sugar with lemon juice until smooth. Add the lemon juice a little at a time to adjust the consistency.
2. Once the muffins are slightly cooled, drizzle the lemon glaze over the top. Let it set for a few minutes before serving.