Preheat oven to 425°F. Spray a 12-cup muffin pan with cooking spray on top (between the cups) and line with squares of parchment paper.
Whisk together flour, baking powder, and salt. Stir blueberries into flour mixture to coat.
Using a stand mixer or handheld mixer, cream butter with sugar for 2 minutes.
Mix in eggs, vanilla, and lemon zest until fully combined.
Alternate adding in dry ingredients with the buttermilk, stirring with a wooden spoon or spatula until just barely combined. If necessary, add an additional tbsp of buttermilk to help the batter come together.
Bake in preheated oven for 8 minutes, then reduce heat to 375°F (without opening oven door).
Bake another 15 minutes or until a toothpick entered into a muffin comes out clean. Let cool in muffin pan for 10 minutes, then serve warm or cool on wire racks.
Buttermilk: I used full fat buttermilk for these muffins, to enhance the richness of the batter. Full fat would be preferable, if you can find it, but low-fat buttermilk works fine as well.Frozen berries: If you use frozen berries, thaw and drain them fully before baking, and then make the muffins as usual.