I was raised on cheese grits casserole. While I love the original, I also love this updated version!!
1½ teaspoons plus 2 tablespoons unsalted butter
½ cup finely grated Parmesan
3 2/3 cups milk (not skim)
1 cup stone-ground or old-fashioned grits
Salt and black pepper
1½ cups grated sharp cheddar
1 clove garlic, minced
1 teaspoon hot pepper sauce
4 large eggs, separated, at room temperature
6 ounces baby spinach leaves (7½ cups loosely packed)
6 scallions thinly sliced (2/3 cup), 1 tablespoon reserved
Grease a 2-quart souffle dish with 1½ teaspoons butter, dust with 3 tablespoons of the Parmesan, and set aside.
In a medium non-stick saucepan bring the milk and the 2 tablespoons of butter to a simmer over medium heat. Add the grits in a slow, steady stream, stirring constantly. Add 1 teaspoon salt, reduce heat to medium-low, and cook, stirring, until grits are thick and begin to pull away from the sides of the pan when you stir, 7 to 10 minutes.
Remove pan from heat and stir in 1¼ cups of the cheddar, the remaining Parmesan, garlic, hot pepper sauce, and black pepper to taste. Set aside to cool slightly, about 15 minutes. Taste the grits and adjust the seasoning, if necessary. Add the egg yolks one at a time, stirring vigorously to incorporate each before adding the next. Stir in the spinach by handfuls.
With an electric mixer, beat the egg whites until they are thick and glossy and hold stiff peaks. Add a quarter of the whites to the grits mixture and, using a spatula, stir until just combined. Add remaining whites and rapidly but gently fold them in along with the scallions.
Spoon the batter into the prepared dish, smooth, sprinkle with the remaining cheddar, and bake at 450 degrees for 10 minutes. Reduce the heat to 375 degrees and continue baking until the souffle is puffed, golden brown, and barely jiggles when you shake the pan, 35 to 40 minutes longer. Sprinkle with reserved scallions and serve at once.