Ingredients
Unsalted butter, melted, for dish
1/2 cup sugar, plus more for dusting
5 ounces bittersweet chocolate, chopped
2 ounces semisweet chocolate, chopped
1 1/3 cups milk
6 large egg yolks plus 8 large egg whites, room temperature
6 tablespoons all-purpose flour
2 tablespoons brandy (optional)
1 teaspoon pure vanilla extract
Salt
Pinch cream of tartar (if not using a copper bowl)
Creme Anglaise
Preparation
Preheat oven to 400 degrees, with rack in lower third. Do not open oven door until ready to bake. Brush 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 sugar (this adds texture, which helps the souffle climb); tap out excess. Chill dish in freezer 15 minutes.
Stir chocolates in a large heatproof bowl set over a saucepan of simmering water until smooth. Scald the milk (heat it until it’s just about to simmer) in a saucepan over medium heat; remove from heat. Using an electric mixer fitted with the whisk, beat 6 tablespoons sugar and the yolks on high until pale, about 4 minutes. On low, beat in flour. Beat in half the hot milk, ladling it in a little at time (this is called tempering and prevents the yolks from scrambling).
Whisk mixture into pan of hot milk; bring to a boil over medium-high heat, whisking. Reduce heat to low; simmer until thick, about 2 minutes. Pour into chocolate. Stir in brandy (if desired), vanilla, and a pinch of salt. (This mixture can be refrigerated, 2 days. Rewarm in a heatproof bowl set over a pan of simmering water.)
Egg whites are best whipped when they’re at room temperature (they attain more volume). Using a balloon whisk, beat whites and a pinch of salt in a copper bowl until foamy. (Or beat with an electric mixer in a stainless-steel bowl with cream of tartar.)
Add 1 tablespoon sugar; beat until whites almost hold stiff peaks. Add remaining tablespoon sugar, and beat until peaks are stiff (meaning they stand straight up when whisk is lifted).
Spoon one-third of egg whites onto base (incorporating in batches prevents them from deflating). Fold them in: Cut through center of mixture with a large rubber spatula, then gently turn spatula over. Rotate bowl a quarter turn; continue folding whites and turning bowl until mostly combined.
Fold remaining whites into base, one-third at a time.
The mixture is ready when the whites are fully incorporated.
Pour mixture into prepared dish. Place on a rimmed baking sheet; this helps you move souffle in and out of oven. Bake 15 minutes. Reduce temperature to 375 degrees; bake until set, 20 minutes. Remove collar; serve immediately with creme anglaise if desired
