Preheat the oven to 375 degrees. Butter one small soufflé dish or four 1-cup soufflé dishes. Dust with flour and shake out the extra.
Melt the butter in a saucepan over medium heat. Sprinkle flour over the top of the melted butter and cook for 1 ½ minutes, whisking the entire time. Add milk, cheese, nutmeg, salt and pepper. Cook while whisking for 3 minutes or until thickened. Remove from heat and whisk in the egg yolks.
Beat the egg whites until stiff peaks form. Gently fold into the cheese mixture. Either pour into the soufflé pan or divide into the 4 individual dishes, and fill 1 inch from the top. Bake until puffed and golden brown and an inserted knife comes out clean, about 12 to 15 minutes. Serve immediately.