Prepare Batter
Cream butter with lemon zest and 1 cup sugar until light and fluffy.
Add egg and vanilla; beat until combined.
Whisk together 2 cups flour, baking powder, and salt.
Add flour mixture to batter, alternating with milk.
Prepare Blueberries
Toss blueberries with ¼ cup flour.
Bake Muffins
Fold blueberries into batter.
Distribute batter among muffin cups.
Sprinkle with remaining 1 tablespoon sugar.
Bake 30 minutes (or 18-25 minutes for a 12-cup tin).
Check with a toothpick.
Cool in pan 7 minutes.
