This post may contain affiliate links. Please read my disclosure policy.
Boston Cream Cake - Two layers of cake sandwiched over a layer of pastry cream and topped with rich chocolate ganache. A delicious dessert.
Boston Cream Cake Ingredients:
1 (18.25 ounce) prepared (according to directions) package yellow cake mix (using eggs, water, vegetable oil)
Boston Cream/Pastry Cream:
- ½ teaspoon unsalted butter
- 1 cup whole milk
- 1 cup heavy whipping cream
- 7 Tablespoons granulated sugar
- 2 Tablespoons cornstarch
- 3 eggs
- 1 to 2 teaspoon vanilla extract, or to taste
- 1 pinch salt
- 4 ounces (high-quality) dark chocolate (bittersweet), chopped
- ½ cup heavy whipping cream
- 1 teaspoon butter
Preheat oven to 350 degrees F (175 degrees C).
Spray 2 (8-inch) cake pans with cooking spray.
Stir yellow cake mix, eggs, water, and vegetable oil in a bowl until moistened. Beat with an electric mixer on medium speed for 2 minutes, scraping bowl occasionally.
Divide cake batter between the two prepared cake pans.
Bake in the preheated oven until cakes have risen and are lightly golden brown, 33 to 38 minutes. Check for doneness after 25 minutes. A toothpick inserted into the center of the cakes should come out clean. Allow cakes to cool for about 10 minutes before removing from the pans. Cool cakes completely, about 40 minutes.
Whisk 3 eggs, cornstarch, and sugar in a large bowl until well mixed and lemon colored, 2 to 3 minutes. Set aside.
Heat 1 cup heavy whipping cream, whole milk, and ½ tablespoon butter in a large saucepan over medium heat until it just begins to boil.
Pour egg mixture into cream mixture and whisk until thick like un-set pudding (about 1 minute) and be careful not to burn.
Pour egg and cream mixture through a fine mesh strainer into a large bowl; discard any chunks.
Whisk vanilla and salt into the egg and cream mixture until combined. Cover with a layer of plastic wrap pressed against the surface. Chill in refrigerator to form a pastry cream texture, 3 to 4 hours.
Place chocolate in a large bowl. Heat 1 teaspoon butter and ½ cup heavy whipping cream in a saucepan over medium heat until butter is melted. Pour cream mixture over chocolate and whisk until smooth. Set aside until cooled, but still pourable, about 20 minutes.
Place one cake layer on a plate, flat side up. Spread pastry cream to within 1-inch of the edge of cake. Place second cake layer on top, rounded side up. Press gently to push pastry cream to the edge. Pour chocolate mixture over top of the cake and spread so it drips over the edge.
Boston Cream Cake
- Pastry Cream Filling:
- 5 large egg yolks
- 2 tablespoons cornstarch
- 2 tablespoons all-purpose flour
- ¼ cup granulated sugar
- 4 tablespoons butter
- 1 cup heavy cream
- 1 cup whole milk
- 1 ½ teaspoons vanilla extract
- pinch of salt
- 1 box yellow cake mix (plus ingredients, bake according to package instructions)
- Chocolate Ganache:
- ½ cup heavy cream
- 4 ounces dark chocolate, chopped
- Make the pastry cream in a large bowl, whisk together the 5 large egg yolks, 2 tablespoons cornstarch, 2 tablespoons all-purpose flour, and ¼ cup granulated sugar, until combined. Set aside.
- In a medium saucepan over medium heat, add in the 4 tablespoons butter and allow it to melt. Add in the 1 cup heavy cream, 1 cup milk, 1 ½ teaspoons vanilla extract, and a pinch of salt. Stir and allow the mixture to come to a low boil.
- Adjust the heat to low and very slowly pour and whisk the egg yolk mixture into the milk mixture until it becomes bubbly and begins to slightly thicken, about 1 to 2 minutes.
- Carefully remove the saucepan from the heat and pour it through a fine-mesh strainer into a large glass mixing bowl. Discard any chunks left in the strainer. Place a piece of plastic wrap over the bowl, allowing it to touch the top of the pastry cream. Place the bowl in the refrigerator and allow it to chill and set/completely thicken for about 3 to 4 hours. *Stir before spreading on the cake.
- Make the cake according to the yellow cake mix package instructions. Be sure to follow the instructions on the box to make 2 round layers.
- Once finished carefully remove the cake pans from the oven and allow them to cool on a rack for about 10 minutes before removing the cakes from the pans to finish cooling completely on a rack.
- Begin assembling the cake by adding one layer to a serving cake plate and topping it with an even layer of pastry cream filling. Leave a small amount (about ⅛-inch) empty around the edge of the cake. Add the second cake layer on top and gently press the top of the cake to allow the pastry cream to fill in the middle.
- In a saucepan over medium-low heat, add the ½ cup heavy cream and allow it to heat for 1 to 2 minutes before adding the 4 ounces dark chocolate. Stir until melted and smooth. Remove the saucepan from the heat and allow it to sit undisturbed for 2 to 3 minutes.
- Whisk the ganache, and pour on top of the cake, spreading it to the edges so that it drips on the sides of the cake. Allow it to sit for 10 minutes before slicing to serve. Enjoy!
- Store the cake in an airtight container in the refrigerator for up to 4 days.