Preheat your oven to 375 degrees and grease a 12-cup muffin tin or line it with paper liners.

Beat the softened butter and sugar together in a large bowl until the mixture looks pale and fluffy.

Add the eggs one at a time, mixing until combined after each addition.

Stir in the vanilla extract and lemon zest.

In a separate bowl, whisk together the flour, baking powder, and salt.

Toss the blueberries with the extra tablespoon of flour in a small bowl until they are evenly coated.

Add the flour mixture to the butter mixture in three parts, alternating with the milk. Stir just until no dry flour remains.

Gently fold in the floured blueberries using a spatula.

Divide the batter evenly among the prepared muffin cups.

Mix the sugar and cinnamon together and sprinkle over the tops of the muffins.

Bake for 18 to 22 minutes, or until the tops are golden and a toothpick inserted into the center comes out with a few moist crumbs.

Cool the muffins in the pan for 5 minutes before moving them to a wire rack.