1 1/2 tablespoons unsalted butter, plus extra for greasing ramekins
2 tablespoons finely grated Parmesan cheese
1 1/2 tablespoons all-purpose flour
1/2 cup whole milk
2 large eggs, separated
1/2 teaspoon ground mustard
1/4 teaspoon salt
1/4 teaspoon white pepper
1/4 to 1/3 cup grated cheese (any type)
1/4 teaspoon cream of tartar
Gather the ingredients.
Grease 2 (1-cup) soufflé dishes/ramekins with butter and dust with Parmesan cheese.
Melt the butter over medium-low heat, then add flour and cook for 3 minutes, stirring constantly.
In the meantime, heat the milk in the microwave at medium power for 30 seconds just to warm.
Whisk warmed milk into the flour and butter mixture and continue to cook, stirring, until thickened.
Whisk together the egg yolks, ground mustard, salt, and white pepper, then add to sauce mixture, whisking quickly to avoid scrambling the eggs.
Stir in the grated cheese, melt and mix thoroughly.
Remove from heat and allow it to cool to room temperature, about 15 minutes. While the custard is cooling, preheat the oven to 425 F.
Beat the egg whites
and cream of tartar to medium-stiff peaks using a hand mixer or standing mixer.
Once medium-stiff peaks form, fold 1/3 of the whites into the room-temperature sauce mixture.
Carefully and delicately fold this mixture back into the remaining whites until just combined.
Divide between the prepared soufflé dishes, place in the oven, reduce the heat to 375 F, and bake 30 to 35 minutes depending on how well done you like your soufflés. A toothpick inserted in the middle should come out mostly clean, with no wet batter attached. Don’t open the oven within the first 20 minutes or the soufflés will deflate.