Step 1

For the Filling: Place chopped chocolate in a medium bowl, add vanilla, and suspend a large, single-mesh sieve over the top. Whisk sugar, salt, espresso powder, cocoa powder, and cornstarch together in a 3-quart stainless steel saucier. Add egg yolks and roughly 1/2 cup of the milk and whisk until smooth before adding the rest of the milk. Cook over medium-low, stirring gently with a whisk until hot to the touch; about 6 minutes.

Step 2

Increase heat to medium and continue whisking gently until thick and bubbly, about 5 minutes (if it's not bubbling by then, feel free to crank up the heat). When you see that first bubble, set a timer and continue whisking exactly 90 seconds. Immediately pour into the sieve, pressing with a flexible spatula until custard passes through. Fold until chocolate has melted into the custard, and cover with a heavy towel.

Step 3

For the Topping: Adjust oven rack to lower-middle position and preheat to 375°F. Prepare Swiss Meringue as directed. Pour custard into the prepared crust, and dollop meringue over top. Gently spread it edge to edge with the back of a fork, using the tines to sculpt it into a pretty design. Place on a wire rack set inside a 13- by 18-inch rimmed baking sheet and bake until well browned, about 15 minutes (this set-up minimizes heat transfer to the custard).

Step 4

To Serve: Cool 1 hour at room temperature, then cover loosely in plastic and refrigerate to an internal temperature of 60°F, about 3 1/2 hours. Cut with a wet chef's knife, rinsing the blade clean with cold water between each slice. Wrapped in plastic, leftovers can be refrigerated up to a week.