- 1 1/2 tablespoons plus 4 tablespoons softened butter, divided
- 3 tablespoons grated Parmesan cheese
- 1 lb. spinach, stemmed and chopped
- 2 tablespoons all-purpose flour
- 1/2 teaspoon salt
- 1 cup whole milk
- 1/8 teaspoon ground black pepper
- 1/8 teaspoon grated nutmeg
- 3 eggs, separated
- Brush the inside of a large soufflé or deep casserole dish with 1 1/2 tablespoons of softened butter.
- Sprinkle the buttered surface evenly with Parmesan cheese and set aside the dish.
- In a large saucepan, sauté the spinach until it wilts and the juices have evaporated.
- Preheat the oven to 375F.
- In a separate medium saucepan, melt the remaining butter over medium heat and stir in the flour and salt.
- Cook the flour, whisking constantly, for 30 seconds.
- Add the milk to the flour and cook, still whisking constantly, for about 4 minutes, until the mixture thickens.
- Add the spinach and continue cooking over medium heat for 1 minute.
- Season the mixture with black pepper and nutmeg.
- Whisk 1/2 cup of the hot spinach into the egg yolks, and then add the egg yolk mixture back into the hot spinach, stirring to completely incorporate.
- Beat the egg whites on high speed until stiff peaks form.
- Stir one-third of the egg whites into the spinach, and then fold the remaining egg whites into the mixture.
- Spoon it into the prepared dish and bake for 30 minutes, until the soufflé is puffed up and cooked through.