In a saucepan over high heat, bring 4 cups water and 1/2 teaspoon salt to a boil. Stir in the grits and return to boil. Reduce heat to very low and simmer, stirring frequently, until thick and creamy, about  15 - 20 minutes for old fashioned grits. Remove pan from heat. Add the butter, cayenne and cheese and stir until the cheese is melted and smooth. Stir in the green onions and let cool until lukewarm. Add the egg yolks and stir until blended.

While grits are cooking preheat oven to 350˚F. Generously butter a 9 x 13 inch baking dish.

In a large bowl, using an electric mixer on high speed, beat the egg whites until they form glossy peaks. Fold about 1/4 of the beaten egg white into the grits then gently fold in the rest. Pour the mixture into the prepared baking dish.

Baked until puffed and goden brown. Serve at once directly from the baking dish.