900g spinach, stalks removed
1 cup milk
1/4 cup flour
1/4 teaspoon salt
1/4 teaspoon white or black pepper
1/8 teaspoon nutmeg
1 cup Cheddar cheese, divided
1 cup cream cheese
3 large egg whites
Preheat oven to 180°C. Coat a shallow baking dish with cooking spray.
Pulse spinach in a food processor until very finely chopped.
Combine milk, flour, salt, pepper and nutmeg in a large saucepan. Cook over medium heat, whisking, until thickened, 2 to 4 minutes. Remove from the heat and stir in 1/2 cup Cheddar, cream cheese and the spinach. Beat egg whites in a large bowl with an electric mixer, slowly increasing the speed, until they begin to foam. Continue to beat until the whites hold their shape; do not over beat. (You’ll know they are ready when you lift the beaters out and the peak doesn’t flop over.) Gently fold the whites into the spinach mixture with a rubber spatula until uniform. (It’s OK if a few white streaks remain.) Transfer to the prepared baking dish. Bake for 35 minutes. Top with the remaining 1/2 cup Cheddar; continue baking until the cheese is melted, about 10 minutes more. Let stand for 5 minutes.