Add the butter to the cast iron skillet. Place the skillet inside the oven and preheat to 450ºF
While the oven is preheating, mix together all of the remaining ingredients in a large mixing bowl. I like to use a hand crank egg beater. Once the oven has reached 450ºF, remove the skillet from the oven and swirl the butter around to fully coat the skillet.
Add the mixture to the hot skillet and place back into the oven
Bake for 25-30 minutes. The middle should look fully set and the sides baking up higher than the center.
Allow it to cool off for about 5 minutes before serving.