1 tbsp butter
⅓ cup sugar, plus some for dish
3 eggs, separated into yolks and whites
2 ounces good quality bittersweet chocolate, melted
¼ teaspoon cream of tartar
1) Preheat oven to 350 degrees.
2) Melt chocolate.
3) Butter two 2-cup or one 4-cup soufflé or other deep baking dish(es). Sprinkle each with sugar, invert it and tap to remove excess sugar.
4) In stand mixer, beat 3 egg yolks with all but 1 tablespoon sugar until very light and very thick; mixture will fall in a ribbon from beaters when it is ready.
5) Add in the melted chocolate, set aside.
6) Wash beaters well, then beat egg whites with salt and cream of tartar until whites hold soft peaks; continue to beat, adding remaining tablespoon sugar, until they are very stiff and glossy.
7) Stir a good spoonful of whites thoroughly into egg yolk mixture to lighten it; then fold in remaining whites, using a rubber spatula.
8) Transfer to prepared soufflé dishes (or cover and refrigerate until you are ready to bake).
9) Bake until center is nearly set, 20 minutes for individual soufflés and 25 to 35 minutes for a single large soufflé. Serve immediately.