Chocolate Soufflé

Preheat the oven to 400°F, with a rack in the lower third. Do not open the oven door until ready to bake. Brush the outer lip of a 2-quart soufflé dish with melted butter. Tie a sheet of parchment around the dish with kitchen twine. Brush the inside of the dish and collar with melted butter. Dust with sugar; tap out excess. Chill the dish in the freezer 15 minutes.

Stir the chocolates in a large heatproof bowl set over a saucepan of simmering water until smooth. Scald the milk 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 speed until pale, about 4 minutes. On low speed, beat in the flour. Beat in half the hot milk, ladling it in a little at time.

Whisk the mixture into the 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 the chocolate. Stir in the brandy (if desired), the vanilla, and a pinch of salt.