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Boston Cream Pie Cake Recipe

Boston Cream Pie Cake

This is a classic American dessert that is technically a cake, not a pie. It's composed of three distinct parts: two layers of light sponge cake, a thick vanilla custard filling, and a glossy chocolate glaze. The single most important rule is to make the custard the day before; it needs to be completely cold and set, otherwise, it will turn into a soupy mess when you try to assemble the cake.
Prep Time45 minutes
Active Time25 minutes
Custard + Refrigerator1 day 2 hours
Total Time1 day 3 hours 10 minutes
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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.

Notes

The custard must be made a day ahead and completely chilled for proper assembly.