3 Tbls unsalted butter plus more for greasing soufflé dish
3 Tbls flour
1 cup scalded milk
a pinch of nutmeg
a pinch of cayenne pepper
Salt and pepper to taste
1/4 cup freshly grated Parmesan cheese, plus more for sprinkling the dish
1/2 cup grated Swiss cheese
10 oz package of chopped spinach thawed and squeezed dry
4 egg yolks
5 egg whites
1/8 tsp cream of tartar
Preheat the oven to 400 degrees. Butter a 6 cup soufflé dish and sprinkle it with Parmesan cheese. Melt the butter in a heavy sauce pan and add the flour. Cook and whisk for about a minute. Add the hot milk off the heat and whisk until it is thick. Return to low heat if it does not thicken. Again off heat, add the two cheeses to the mixture. Separate the eggs in two bowls, discarding or saving one of the egg yolks. Beat the egg yolks. Slowly add the egg yolks to the cheese sauce while whisking. Add the seasoning and spinach and stir to combine.
Add the 1/8 tsp cream of tartar to the egg whites and beat them until firm and glossy peaks form. Whisk one quarter of the egg whites into the cheese sauce to lighten, and then fold in the rest. Pour into the prepared soufflé dish, then smooth the top. Draw a large circle on top with the spatula and place in the middle of the oven. Turn the temperature down to 375 degrees. Bake for 30 to 35 minutes until puffed and brown. Serve immediately.