Ingredients
For the Custard Filling (Make a Day Ahead)
- 2 cups whole milk
- 1.5 teaspoons vanilla bean paste
- 1/2 teaspoon Diamond Crystal kosher salt
- 5 large egg yolks
- 1/2 cup granulated sugar
- 1/4 cup cornstarch
- 3 tablespoons cold unsalted butter, cubed
For the Sponge Cake
- 1 1/2 cups cake flour
- 1 1/4 teaspoons baking powder
- 3/4 teaspoon Diamond Crystal kosher salt
- 3/4 cup buttermilk
- 6 tablespoons unsalted butter, cubed
- 2 teaspoons vanilla extract
- 3 large eggs, at room temperature
- 1 cup granulated sugar
For the Chocolate Glaze
- 1/2 cup heavy cream
- 1.5 tablespoons light corn syrup
- 4.5 ounces bittersweet chocolate (60-70% cacao), finely chopped
- A pinch of kosher salt
Make the Custard a Day in Advance
In a medium saucepan, heat the milk, vanilla bean paste, and salt over medium heat until it is steaming and small bubbles form around the edges.
While the milk heats, whisk the egg yolks and sugar together in a medium bowl until pale and smooth. Whisk in the cornstarch.
To temper the eggs, slowly stream about 1 cup of the hot milk into the yolk mixture while whisking constantly. Pour the tempered yolk mixture back into the saucepan.
Cook over medium heat, stirring constantly with a spatula, for ~5-8 minutes. The custard is done when it is very thick and coats the back of the spatula. Strain the custard through a fine-mesh sieve into a clean bowl. Stir in the cold butter until melted. Press a piece of plastic wrap directly onto the surface and refrigerate overnight.
Bake the Sponge Cake Layers
Preheat your oven to 325F. Butter two 9-inch round cake pans and line the bottoms with parchment paper.
In a medium bowl, whisk together the cake flour, baking powder, and salt.
In a small saucepan, warm the buttermilk and butter over low heat until the butter is just melted. Remove from the heat and stir in the vanilla.
In the bowl of a stand mixer, whip the eggs and sugar on high speed for ~4-5 minutes, until the mixture is thick, pale, and ribbony.
On low speed, alternate adding the flour mixture and the warm milk mixture to the whipped eggs, beginning and ending with the flour. Mix only until just combined.
Divide the batter evenly between the prepared pans. Bake for ~20-25 minutes, until a toothpick inserted into the center comes out clean. Let the cakes cool in the pans for 10 minutes before inverting them onto a wire rack to cool completely.
Assemble the Cake and Glaze
Place one cooled cake layer on a serving plate. Stir the chilled custard to loosen it, then spread it evenly over the cake, leaving a small border. Place the second cake layer on top. Chill the assembled cake for at least 30 minutes.
To make the glaze, heat the heavy cream and corn syrup in a small saucepan until simmering. Pour the hot cream over the chopped chocolate in a bowl, add the salt, and let it sit for 5 minutes. Stir until the glaze is completely smooth.
Let the glaze cool and thicken for about 10-15 minutes, then pour it over the center of the chilled cake, using a spatula to gently guide it over the edges. Refrigerate the finished cake for at least 2 hours to allow the glaze and custard to set firmly before slicing.
Boston Cream Pie Cake
Ingredients
- For the Custard Filling (Make a Day Ahead)
- 2 cups whole milk
- 1.5 teaspoons vanilla bean paste
- 1/2 teaspoon Diamond Crystal kosher salt
- 5 large egg yolks
- 1/2 cup granulated sugar
- 1/4 cup cornstarch
- 3 tablespoons cold unsalted butter cubed
For the Sponge Cake
- 1 1/2 cups cake flour
- 1 1/4 teaspoons baking powder
- 3/4 teaspoon Diamond Crystal kosher salt
- 3/4 cup buttermilk
- 6 tablespoons unsalted butter cubed
- 2 teaspoons vanilla extract
- 3 large eggs at room temperature
- 1 cup granulated sugar
For the Chocolate Glaze
- 1/2 cup heavy cream
- 1.5 tablespoons light corn syrup
- 4.5 ounces bittersweet chocolate 60-70% cacao, finely chopped
- A pinch of kosher salt
Instructions
- Heat the milk, vanilla bean paste, and salt in a medium saucepan until steaming with small bubbles around the edges.
- Whisk the egg yolks and sugar until pale, then whisk in the cornstarch.
- Slowly stream 1 cup of the hot milk into the yolk mixture while whisking constantly.
- Pour the tempered mixture back into the saucepan and cook over medium heat, stirring constantly until very thick, about 5-8 minutes.
- Strain the custard through a fine-mesh sieve, stir in the cold butter until melted.
- Cover the custard with plastic wrap directly on the surface and refrigerate overnight.
- Preheat your oven to 325F and prepare two 9-inch cake pans with butter and parchment paper.
- Whisk together the cake flour, baking powder, and salt in a bowl.
- Warm the buttermilk and butter over low heat until the butter melts, then stir in the vanilla.
- Whip the eggs and sugar on high speed for 4-5 minutes until thick and pale.
- Alternate adding the flour mixture and warm milk mixture to the eggs on low speed, starting and ending with flour.
- Divide the batter between the pans and bake for 20-25 minutes until a toothpick comes out clean.
- Cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely.
- Place one cake layer on a serving plate and spread with the chilled custard, leaving a small border.
- Top with the second cake layer and chill for 30 minutes.
- Heat the cream and corn syrup until simmering, pour over the chocolate and salt, let stand 5 minutes.
- Stir the glaze until smooth and let cool for 10-15 minutes.
- Pour the glaze over the center of the cake, spreading to the edges.
- Refrigerate for at least 2 hours before serving.
