Preheat the oven to 400 degrees F and place the cast iron skillet with the butter in the oven to melt
Separate the egg whites from the yolks into two medium-sized bowls
Using a hand mixer, whip the egg whites for about 4 minutes, or until they are firm and fluffy
Add all the remaining ingredients into the bowl with the egg yolks and whisk using the hand mixer until smooth
Fold the egg whites into the batter and mix with a spatula with a scooping and folding motion until the egg whites are homogeneously incorporated
Remove the hot cast iron skillet from the oven and pour the pancake batter over the melted butter
Bake in the preheated oven for about 12-15 minutes, or until the center is firm, but not overbaked and dry
Slice and serve immediately with your choice of toppings such as fresh fruit, whipped cream, butter, honey or maple syrup