Savory Cheese Soufflé Recipe

Name: Savory Cheese Soufflé Recipe
Prep time: 25 min
Cook time: 50 min
Total time: 1 h 15 min
Cuisine: French
Ingredients: 3 tablespoons (45g) unsalted butter, plus more for greasing the dish; Grated Parmigiano-Reggiano or Grana Padano cheese, for dusting the dish; 3 1/2 tablespoons (1 ounce; 28g) all-purpose flour (see note); 1 cup (235ml) whole milk; Kosher salt and freshly ground black pepper; 1 teaspoon (5ml) Dijon mustard (optional; see note); 1 pinch cayenne pepper or two dashes hot sauce (optional; see note); 4 large egg yolks; 5 large cold egg whites; 1/2 teaspoon cream of tartar (optional; see note); 3 ounces (85g) freshly grated Gruyère or other semifirm cheese, such as cheddar