Salted-Caramel Cream Puffs with Warm Chocolate Sauce

In a medium bowl, whisk the egg with the egg yolks, cornstarch and 1/2 cup of the milk until smooth. In a small saucepan, heat the remaining 1 1/2 cups of milk over low heat; keep warm.

In a medium saucepan, combine the sugar with 1/4 cup of water. Cook over moderate heat, swirling the pan and brushing down the side with a wet pastry brush, until the sugar dissolves. Cook undisturbed until a deep-amber caramel forms, about 5 minutes. Remove the saucepan from the heat and whisk in the butter; be careful, it will boil vigorously. While whisking constantly, slowly drizzle in the warm milk until blended; the mixture may separate a little. Slowly whisk in the egg mixture and bring to a boil, then cook over moderate heat, stirring, until thickened, about 2 minutes. Stir in the vanilla and sea salt. Strain the caramel custard through a fine sieve into a heatproof bowl. Press a piece of plastic wrap directly onto the surface of the custard and refrigerate until completely chilled.

Preheat the oven to 400º. Line a baking sheet with parchment paper or a silicone mat.

In a medium saucepan, combine the water, butter, sugar and salt. Cook over moderate heat for 1 minute, until the butter dissolves. Add all of the flour at once and stir vigorously with a wooden spoon, then cook until the dough pulls away from the side of the pan, 1 to 2 minutes. Remove the saucepan from the heat and let stand for 2 minutes, stirring a few times to cool down the dough. Add the eggs one at a time, beating constantly and thoroughly with a wooden spoon between additions: the dough should be smooth and shiny.

Transfer the dough to a pastry bag fitted with a 1/2-inch plain tip. Pipe the dough into twenty-four 1 1/2-inch mounds on the prepared baking sheet, spacing them 1 inch apart. Bake for about 25 minutes, until the tops and bottoms are golden. Transfer the baking sheet to a rack. Using a skewer, poke a small hole in the side of each cream puff to allow steam to escape; let cool completely.

In a medium saucepan, combine the half-and-half, cocoa, corn syrup and sugar. Bring to a boil over moderate heat, stirring occasionally. Remove from the heat. Stir in the butter and chocolate until melted and the sauce is smooth.

Scrape the custard into a piping bag fitted with a 1/4-inch plain tip. Pipe the cream into the hole in the side of each cream puff until full. Drizzle with some of the chocolate sauce, sprinkle with garnishes and serve.