- 4 tablespoons unsalted butter
- 2 tablespoons grated Parmesan cheese
- 1 cup leeks, white parts only, washed, chopped (about 1 large leek)
- 3 tablespoons all-purpose flour
- 1 cup hot milk
- 1/2 teaspoon salt
- pinch of cayenne pepper
- pinch of nutmeg
- 5 eggs, separated, at room temperature
- 1/4 teaspoon cream of tartar
- 1 cup grated Gruyere cheese
- 6 ounces bacon, cooked crisp and crumbled
Preheat the oven to 400º F.
Butter a 6-cup souffle or straight sided baking dish with 1 tablespon of the butter. Dust the interior of the dish with the Parmesan and knock out the excess.
In a medium-size sauté pan, melt 1 tablespoons of butter over low heat, and gently cook the leeks until they are tender, about 10 minutes. Set aside to cool when done.
To prepare the soufflé base, melt the remaining 2 tablespoons of butter in a medium-size sauce pan. Stir in the flour using a wooden spoon and cook for 2 to 3 minutes, stirring frequently, until the mixture begins to foam. Remove the pan from the heat and whisk in the hot milk. Simmer the mixture over medium heat until it becomes thick, about 2 minutes.
Remove the pan from the heat and whisk in the salt, cayenne, and nutmeg; slowly add the egg yolks one by one. Set aside.
In a stainless steel or copper bowl, slowly begin to whisk the egg whites using an electric mixer on medium low speed. Once the egg whites are frothy, add the cream of tartar and a pinch of salt and increase the speed of the mixer to medium and then to medium high. Beat the whites until stiff and they form shiny peaks being careful not to overbeat them.
Add the leeks, half of the Gruyere and the bacon to the soufflé base along with 1/4 of the egg whites and mix well. Delicately fold the remaining whites along with the remaining cheese into the base, being careful not to overmix. It is fine to have a some unblended whites.
Pour the mixture into the prepared soufflé dish and set in the oven. Reduce the oven temperature to 375º F. Bake until the soufflé has puffed and is golden brown, about 25 to 30 minutes.