Boston Cream Doughnuts

Cut 2 tablespoons of the unsalted butter into cubes and place in a small bowl. Let sit at room temperature until softened.

Pour 6 tablespoons of the whole milk into a medium microwave-safe bowl. Microwave until just warm to the touch, about 10 seconds. Sprinkle with 1 packet active dry yeast and let sit until bubbly and foamy, about 5 minutes.

Place 1 3/4 cups all-purpose flour, 2 tablespoons of the granulated sugar, and 1/2 teaspoon of the kosher salt in the bowl of a stand mixer and whisk to combine. Add the milk mixture, 1 large egg, and 1 of the large egg yolks. Beat with the dough hook on medium-low speed until a dough forms (it does not need to be completely smooth), about 3 minutes.

Add the 2 tablespoons room temperature unsalted butter. Mix on medium-low speed until incorporated, about 1 minute. Increase the speed to medium-high and beat until the dough is smooth and elastic, 4 to 5 minutes more.

Coat a large bowl with vegetable oil. Using your hands, gather the dough into a ball. Place in the bowl and cover the bowl with plastic wrap. Let sit in a warm spot until almost doubled in bulk, about 1 hour. Meanwhile, make the pastry cream.

Place the remaining 1/2 cup of the granulated sugar, remaining 4 large egg yolks, 1/4 cup cornstarch, and 1/8 teaspoon of the kosher salt in a small saucepan and whisk until combined and lightened in color. Add 2 cups of the whole milk, 1 teaspoon vanilla extract, and 2 tablespoons of the unsalted butter. Stir to combine, the butter will stay in a chunk.

Place the saucepan over medium-high heat and cook, stirring constantly, until the butter melts and the mixture comes to a boil, about 8 minutes. Let boil, stirring constantly and scraping the bottom of the saucepan to make sure nothing sticks, until thickened, about 1 minute. Immediately scrape the mixture into a medium heatproof bowl.

Press a sheet of plastic wrap directly onto the pastry cream to prevent a skin from forming. Let cool to room temperature. Refrigerate until completely cooled, about 1 hour.

Lightly dust a work surface with all-purpose flour. Place the dough on the surface and roll out with a rolling pin until about 1/2-inch thick. Use a 3-inch round cutter and cut out as many rounds as you can. Gather the scraps in a ball, then re-roll and cut until you have 6 total rounds. Cover with plastic wrap and let rise until doubled in size, about 30 minutes.

Heat 6 cups vegetable oil in a large pot or Dutch oven over medium heat until 350°F. Meanwhile, fit a wire rack onto a baking sheet.

Using a lightly floured thin metal spatula, transfer half of the doughnuts into the hot oil. Fry until golden brown and puffed, about 2 minutes per side. e a kitchen spider or slotted spoon to transfer them to a wire rack to cool. Repeat frying the remaining doughnuts. Let cool before filling.

Whisk the pastry cream until smooth. Transfer into a pastry bag fit with a coupler and 1/4-inch round pastry tip. Insert the tip into the side of each doughnut and fill with pastry cream.

Chop 2 ounces bittersweet chocolate. Place in small saucepan. Add 1 cup powdered sugar, remaining 1/4 cup whole milk, 1/4 cup cocoa powder, remaining 1 tablespoon unsalted butter, and remaining 1/8 teaspoon kosher salt. Place over medium-low heat, and cook, stirring constantly, until melted, combined, and thickened, 3 to 4 minutes. Scrape into a shallow bowl.

Dip the tops of doughnuts into the chocolate sauce, let the excess drip back into the bowl, and return to the wire rack glazed-side. Let sit until the glaze is set, about 45 minutes.