1cupGruyere cheeseor whatever cheese you have on hand
Preheat oven to 400 degrees.
In a medium saucepan, melt the butter. Mix in the flour and salt and stir until you create a paste. Gradually, whisk in milk until smooth. Cook over medium heat, stirring continuously until mixture comes to a boil.
Reduce heat to low and whisk until thickened.
Add cheese. Stir until well mixed. Remove from heat.
Beat egg whites with an electric or stand mixer until they form stiff peaks.
Stir egg yolks into cheese sauce until well blended.
Slowly fold cheese mixture into the egg whites until well incorporated.
Lightly grease ramekins (or soufflé dish) and dust with parmesan cheese to coat sides.
Transfer mixture into ramekins.
Place in oven and turn heat down to 375 degrees.
Bake 30 minutes or until soufflé puffs up and is browned.