Using a stand mixer, cream butter and sugar together on medium high speed until light and fluffy, about 2-3 minutes. Scrape sides.
In a medium sized bowl, combine cornmeal, flour, baking powder, and salt. In a separate bowl, combine eggs and buttermilk. Add wet ingredients to the butter and sugar mixture and mix just until combined. Scrape sides. Add dry ingredients and mix until combined.
Using a 10" skillet for thick cornbread or 12" skillet for thinner cornbread, add 2 tablespoons of butter and heat pan in preheated oven or on stove over medium high heat until the butter is melted and the pan is hot. Spread butter around the bottom and up the sides. Immediately pour batter into skillet and place in preheated oven. Cook for 10 minutes in 400 °F oven. Then, without opening the door, reduce oven temperature to 300 °F and continue cooking for 30 minutes (cooking time will be less if using larger 12" skillet). Remove from oven when cake tester inserted into the middle comes out clean and the top is golden brown.
Allow to cool slightly in pan before slicing. Cornbread will slice better if it has fully cooled.
Notes
Frozen vs. Fresh Corn: If using frozen, be sure to thaw fully before incorporating into the cornbread batter to ensure even cooking. If using fresh corn, use a knife to separate them from the cob and be sure to scrape the cob with the knife to also include any liquid.
Buttermilk substitution: Don't have buttermilk? You can easily use milk (whole milk recommended) in lieu of the buttermilk in this recipe. You can also make a buttermilk substitute by adding a tablespoon of lemon juice to whole milk and letting it sit for at least 15 minutes before adding to the batter.
Slicing: If you want pretty slices, you'll have to wait until the cornbread has cooled. If you try to remove hot cornbread from the pan, it will likely fall apart.
Storage: Store leftover cornbread in an air tight container in the refrigerator. Should keep for at least 3-5 days.
Reheating: Warm cornbread is the best. To reheat, place in microwave at 50% power in one minute increments. Likewise, you can reheat in a toaster oven or the main oven. You'll just want to place the cornbread in a dish or on foil to prevent crumbs from falling.
Skillet size: A 10" skillet will produce thick cornbread and will take longer to cook. This recipe can also be made in a 12" skillet with a reduced cooking time.