Ingredients

1/2 cup sugar 

1/4 cup cornstarch 

Pinch of coarse salt 

1 1/2 cups whole milk 

1/2 cup strong, freshly brewed espresso 

4 large egg yolks 

2 tablespoons unsalted butter 

1 teaspoon pure vanilla extract 

1/2 cup (1 stick) unsalted butter, cut into small pieces 

1 teaspoon sugar 

1/2 teaspoon salt 

1 cup water 

1 cup all-purpose flour 

4 large eggs 

4 ounces semisweet chocolate (61%), chopped 

1/2 cup heavy cream

Preparation

Prepare the pastry cream: Whisk together sugar, cornstarch, and salt in a medium saucepan. Whisk together milk, espresso, and egg yolks in a glass measuring cup. Add milk mixture to saucepan, along with butter. Cook over medium heat until mixture comes to a boil. Let boil 1 minute. Remove from heat and add vanilla.

Strain pastry cream through a fine-mesh sieve into a bowl. Cover with plastic wrap, pressing it directly onto the surface of the pastry cream to prevent a skin from forming. Refrigerate until chilled, at least 2 hours or up to 2 days.

Prepare the puffs: Preheat oven to 400 degrees. In a medium saucepan over medium-high heat, combine butter, sugar, salt, and water. Bring to a boil and immediately remove from heat. Using a wooden spoon, quickly stir in the flour until combined.

Return pan to medium-high heat and cook, stirring vigorously, until mixture pulls away from the sides and a film forms on the bottom of the pan, about 3 minutes.

Remove from heat and add eggs, one at a time, stirring vigorously after each addition, and waiting to add the next egg until the previous one is entirely incorporated.

Transfer dough to a pastry bag fitted with a 3/4-inch plain round tip (#809). On two parchment-lined baking sheets, pipe sixteen 2-inch rounds. Gently smooth the pointed peaks with a moistened finger, rounding tops to ensure even rising. Bake, rotating halfway, until puffed and deep golden-brown, 30 to 35 minutes. Transfer to a rack. Using a paring knife, make a small “X” in the bottom of each puff. Let cool completely.

Whisk the pastry cream until smooth and transfer to a pastry bag fitted with a 1/4-inch filling pastry tip (#230). Fill each puff with some of the pastry cream.

Make the glaze: Place the chocolate in a medium bowl. Bring the cream to a boil in a small saucepan over medium heat. Pour the hot cream over the chocolate; let stand 1 minute. Whisk until smooth. Dip the top of each cream puff in the chocolate and let stand at room temperature to set, about 20 minutes.