Ingredients
4 tablespoons unsalted butter, plus more, melted, for dish
1 cup finely grated Parmesan cheese, plus more for dusting
1 large shallot, finely chopped
6 tablespoons all-purpose flour
1 1/2 cups milk
2 tablespoons chopped fresh rosemary
2 tablespoons chopped fresh thyme
Generous pinch of freshly grated nutmeg
Pinch of cayenne pepper
1 cup grated Gruyere cheese
Coarse salt and freshly ground pepper
6 large egg yolks plus 8 large egg whites, room temperature
Pinch cream of tartar (if not using a copper bowl)
Preparation
Preheat oven to 400 degrees, with rack in middle. Brush the outer lip of a 2-quart souffle dish with melted butter. Tie a sheet of parchment around dish with kitchen twine so it extends 3 inches above rim. Brush inside of dish and collar with melted butter. Dust with Parmesan cheese; tap out excess. Chill dish in freezer 15 minutes.
Heat butter in a medium saucepan over medium heat. Add shallot; cook until soft, 3 to 4 minutes. Add flour; cook, whisking, 3 minutes. Whisk in milk, herbs, and spices. Bring to a boil. Reduce heat to low; whisk until thick, about 4 minutes. Add cheeses; whisk until melted. Season with 1 teaspoon salt, and pepper to taste. Pour into a bowl; stir in yolks.
Using a balloon whisk, beat whites and a pinch of salt in a copper bowl to stiff peaks. (Or beat with an electric mixer in a stainless-steel bowl with cream of tartar.)
Spoon one-third of whites onto base. Fold them in: Cut through center of mixture with a large rubber spatula; gently turn spatula over. Rotate bowl a quarter turn; continue folding whites and turning bowl until mostly combined. Fold in remaining whites, one-third at a time.
Pour mixture into prepared dish. Bake 15 minutes. Reduce temperature to 375 degrees;bake until set, 16 to 18 minutes. Remove collar, and serve immediately.
