2 tablespoons unsalted butter, softened
½ cup sugar plus more to sugar the ramekins
1/3 cup unsweetened cocoa powder
¼-cup all-purpose flour
2 ¾ cups heavy cream
2 vanilla beans, preferably Tahitian
4 large eggs at room temperature, separatjed
6 drops lemon juice
2 tablespoons confectioner’s sugar
1 cup crème anglaise
Have 5 6-ounce soufflé cups (or ramekins) on hand. Spread the butter on the inside, then coat with the extra sugar, swirling it around and transferring excess sugar into the next ramekin. Repeat to coat all the ramekins. Reserve.
Preheat the oven to 390° for conventional oven (365° convection).
In a medium saucepan off the heat, combine ¼ cup of the sugar, the cocoa powder, and flour with a whisk, making sure to combine completely. Slowly whisk in the heavy cream, making sure that there are no lumps. Scrape the seeds of the vanilla bean into the cream. Over medium-low heat, cook the mixture, stirring with a heat-proof rubber spatula constantly until the mixture is just barely at a simmer, and slightly thickened, about 8-10 minutes.
Meanwhile, in a large bowl, whisk the egg yolks just to combine them. Temper a few small ladles of the hot cream mixture into the yolks in a thin stream. Transfer the tempered yolks back into the cream pot. Over low heat, stirring constantly with a flat-edged rubber spatula, cook the mixture for about 8-10 minutes until thickened and the first heat bubble breaks the surface. Immediately, transfer the pastry cream into to a non-reactive pan set in an ice bath, making sure not to scrape any hard film from the sides and bottom of the pan. Remove the vanilla bean. Cover the surface with plastic wrap, making sure the wrap touches the surface to prevent a film from forming. Cool completely. Transfer 1½ cups of pastry cream into a large bowl and reserve. (Save remaining pastry cream to eat as chocolate pudding.)
As soon as the pastry cream has cooled, make the meringue: In a stand mixer fitted with a whisk attachment or using a hand blender, add the egg whites and lemon juice and start whisking on low, then gradually increasing the speed to medium. After about one minute, when the foam whitens and bubbles a little, very gradually add the remaining ¼ cup of sugar, about ½ teaspoon at a time. Increase the speed to high and continue to whisk just until the meringue forms a “sparrow’s beak,” when it is pulled upward with the whisk attachment and is shiny, about 2 additional minutes.
Gently fold about ½ cup of the meringue mixture into the chocolate pastry cream to lighten it. Fold in the remaining meringue, being careful to mix it until just homogenous with no clumps of egg white visible.
Gently transfer the mixture into the prepared soufflé cups. Be sure to only fill into the center of the cup, not allowing the mixture to touch the rim of the ramekins. Gently fill to the height of the rim. Run the side of your thumb along the top and just inside the rim of the ramekin to clean it off completely, to ensure that the soufflé will rise. Place all the ramekins on a rimmed sheet tray. Bake about 17 minutes. The soufflés will have risen about ½- to ¾-inch over the top of the ramekin.
To serve: As soon as they are done are, carefully place the soufflés on individual serving liners. Have the confectioner's sugar in a small sieve and dust the tops of the soufflés with the sugar. Using the tip of a spoon, gently break the surface of the soufflé to create a small hole in the center. Spoon 2 to 3 tablespoons of crème anglaise into the hole and serve immediately.