Source: Archa Wachowicz
3 Tbsp. butter
3 Tbsp. flour
1 1/2 cups milk
5 eggs, separated
1/2 tsp. salt
freshly ground black pepper
1/2 tsp. dry mustard
1 1/12 cups grated cheese - whatever is on hand - gruyere, swiss, cheddar, etc.
1 Tbsp. & 1 Tbsp. grated parmesan cheese (to dust the container)
Preheat oven to 370 degrees. Butter the bottom and sides of a 2 1/2 or 3 quart soufflé dish, then dust the dish all around with 1 Tbsp of the grated parmesan.
Make a roux with the butter and flour, then add the milk, whisking until thick and smooth. Reduce heat and quickly whisk in the egg yolks, then stir in the spices and cheese, stirring until melted.
Remove mixture from heat and let cool. Meanwhile beat the egg whites until stiff. When the roux mixture has cooled down enough (need not be cold), stir a dollop of egg whites into the mixture normally, then gently fold in the rest of the whites until the batter appears somewhat uniform.
Pour batter into baking dish and pop into oven. Cook until souffle is puffed and brown on top - about 30 minutes.