Add cream of tartar to the whites while beating; the acid stiffens and coagulates the egg-white protein, strengthening the walls of the bubbles. Sugar, used in sweet soufflés, also strengthens the bubbles.

Use a wire whisk attachment to introduce air into the whites evenly, creating tiny, strong bubbles.

Beat the whites just until stiff but moist-looking peaks form. If the whites are overbeaten, the walls of the air bubbles will be stretched out; they may burst when heated, collapsing the soufflé.

Fold the white sauce gently but thoroughly into the beaten egg whites, using a flexible spatula. Overmixing, or folding with a heavy hand, may collapse the egg-white bubbles, leaving your soufflé less than ethereal.

Bake the soufflé in the right dish size for the best results. Classic soufflé dishes aren’t necessary; you can also use deep casseroles or ovenproof bowls, though soufflés baked in bowls with sloping sides won’t rise as high as those in straight-sided dishes. Measure your dish’s capacity with water to determine its volume.

 

3 tablespoons butter

3 tablespoons all-purpose flour

1 cup milk

1 cup chopped bittersweet or semisweet chocolate (5 to 6 oz.)

4 large eggs, separated

2 tablespoons rum or 1 teaspoon vanilla

1/8 teaspoon cream of tartar

1/4 cup sugar

Lightly sweetened softly whipped cream

 

Generously butter four 1- to 1 1/4-cup soufflé dishes or one 1 1/2-quart soufflé dish. If using small dishes, set them slightly apart in a 10- by 15-inch baking pan. In a 2- to 3-quart pan over medium heat, melt 3 tablespoons butter. Add flour; stir until mixture is smooth and bubbling. Stir in milk; continue stirring until sauce boils and thickens, about 2 minutes. Remove from heat. Add chocolate and stir until smooth. Add egg yolks and rum and stir until mixture is blended and smooth. In a bowl, with a mixer on high speed, beat egg whites (use whisk attachment if available) with cream of tartar until foamy. Gradually add sugar and continue beating until short, stiff, moist peaks form. With a flexible spatula, fold a third of the chocolate sauce into whites until well blended. Add remaining sauce and gently fold in just until blended. Scrape batter into prepared soufflé dishes; if higher than 3/4 full, use foil collar (see “Crowning Glory” below). Bake in a 375° regular or convection oven to desired doneness: For a soft, creamy center, bake until edges feel set and dry but center 1 to 1 1/2 inches of small soufflés or 2 to 3 inches of large one still appear soft and jiggle slightly when dishes are very gently shaken, 12 to 15 minutes for small soufflés, 15 to 20 minutes for large one. For a fully set center, bake until surface appears set and fairly dry, 2 to 3 minutes longer for small soufflés, 5 to 6 minutes longer for large one. Serve at once, scooping portions from single soufflé with a large spoon. Offer whipped cream to add to taste.

 

Crowning glory

Soufflés look most impressive when they rise dramatically over the rim of the dish. To create a beautiful crown on your soufflé, fill the dish about 3/4 full. If it’s less full, the soufflé may not rise over the rim. If it’s more full, the soufflé may spill over unless you wrap the dish with a foil collar. Here’s how to make one.

Cut a 15-inch-wide sheet of foil 4 inches longer than circumference of dish; fold lengthwise in thirds. Coat one side of the foil strip generously with melted butter, using a pastry brush. Wrap the foil around outside of dish so that at least 2 inches of foil extend above the rim. Fold the ends of the buttered foil strip over several times until snug against dish.