Gently stir the dry ingredients into the wet ingredients until just combined.
Divide batter between 12 muffin tin cups, filling ¾ of the way full.
Bake for 15-20 minutes or until a toothpick inserted in the center of the muffin comes out clean.
Allow muffins to cool for 1-2 minutes before transferring from the pan to a cooling rack.
Serve warm with butter.
Notes
Vegetable oil: Any neutral oil will work in this recipe.
Whole milk: The fat in the whole milk helps to make the muffins moist. Another type of milk, like skim or 1%, can be used, but the muffins won't be as moist or as tender.
Salted butter: If you prefer to use unsalted butter, increase the salt to 3/4 teaspoon.
Yellow cornmeal: Feel free to use white cornmeal if you prefer.
Sugar: The amount of sugar can be adjusted according to your tastes. I usually use 1/3 cup, and that amount gives me a lightly sweet muffin.