Preheat oven to 375 degrees. Liberally grease a muffin tin with non-stick cooking spray. We aren't using liners, so make sure to spray them well!
In a large bowl, add cornmeal, flour, sugars, baking powder, baking soda, and salt. Whisk until combined.
Add butter, eggs, and buttermilk to another small bowl or large measuring cup. Whisk to combine.
Add wet ingredients to dry ingredient. Use a spatula or wooden spoon to mix the ingredients together just until they're combined. Use an ice cream scoop to fill muffin tins about 3/4 full.
Bake muffins until golden brown and cooked through, about 12-13 minutes. A toothpick when inserted should come out with a few dry crumbs attached.