Preheat the oven to 425F. Line a 12 cup muffin tin with papers or grease well with oil.
Stir together the flour, cornmeal, granulated sugar, baking powder, and salt in a mixing bowl.
Pour in the milk, melted butter, and whisked egg, stirring until just combined. In a small bowl, toss the blueberries with 1 tablespoon of flour. Fold the blueberries into the cornbread mixture.
Scoop ¼ cup batter into each muffin tin. Bake at 425F for 5 minutes, then reduce the oven temperature to 350F and bake for an additional 15-18 minutes. Don't open the oven door. This is what gives the corn muffins their domed appearance.
The muffins are ready when domed, firm on top, and golden around the edges. Enjoy!
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Notes
Cornmeal: I use standard fine yellow cornmeal. I've had success with using coarse cornmeal in cornbread in the past, but I haven't tested it with this recipe.
Blueberries: If using frozen blueberries, make sure they are completely thawed and patted dry before using.
Best within 4-5 days. I like to keep corn muffins refrigerated because they are very moist.
How to freeze: Let the muffins cool to room temperature before transferring to a freezer bag or container. Freeze for up to 3 months. Let cool at room temp or pop in the microwave to reheat.