Best Ever Corn Muffins

Preheat oven to 375 degrees F (190 degrees C). Grease 12 muffin cups or line with paper muffin liners.
In a large bowl, cream together the butter and sugar until light and fluffy. Stir in the eggs one at a time, beating well with each addition, then stir in the vanilla.
In a separate bowl, stir together baking mix and cornmeal. Blend this mixture into the butter/egg mixture, alternately with the milk; stir just until combined. Spoon batter into prepared muffin cups.
Bake in preheated oven for 20 to 30 minutes, until golden.