Cheesy Grits Soufflé Casserole

Ingredients

• 2 cups water
• 2 cups whole or 2% milk
• 1 teaspoon kosher salt
• 1 cup grits (I prefer yellow, but white grits are fine)
• 2 to 4 tablespoons unsalted butter
• 2 cups grated cheddar cheese
• 1/8 teaspoon cayenne pepper
• 1/8 teaspoon black pepper
• 1/2 cup thinly sliced scallions or chives, optional
• 3 large eggs
• 1/2 cup sour cream