Boston Cream Pie
Classic Boston cream pie features moist vanilla sponge cake layers that are sandwiched with pastry cream and topped with a rich chocolate ganache. This decadent cake recipe is well worth the extra effort!
Surprise! This “pie” recipe is actually a layer cake.
Boston cream pie dates back to the mid-nineteenth century. Because pie plates were used more often than cake pans, the original recipe was made in a pie plate so it was dubbed a Boston cream pie.
Whatever you want to call it, this recipe for Boston cream pie is rich, decadent, and full of flavor.
First, you have the moist vanilla sponge cake layers. They’re sandwiched with pastry cream, then some homemade chocolate ganache is spread all over the top of the cake.
If you’ve never tried a bite of Boston cream pie before, get ready to fall head over heels for your new favorite dessert!
As I’ve already mentioned, this recipe has three components: the sponge cake, the pastry cream filling, and the chocolate ganache topping. I’ve shared the full list of ingredients in the recipe card below, but here’s a quick overview of some of the key ones.
- Whole milk: Is used in both the pastry cream and sponge cake batter. I recommend using whole milk rather than 2% or skim to ensure the pastry cream sets properly and the cake remains moist.
- Eggs: The pastry cream calls for just egg yolks, and the cake batter uses whole eggs. Don’t confuse the two when making the recipe!
- Cornstarch: Helps thicken the pastry cream. Do not omit it, otherwise the pastry cream won’t set up properly.
- Flour: Be sure to spoon and level the flour when measuring it, otherwise you may measure out too much by mistake.
How to Make a Boston Cream Pie
This is an easy Boston cream pie recipe, but it does require more prep work than your average layer cake. I recommend making the pastry cream first so that it has time to fully chill before you assemble the cake.
- Whisk together the ingredients: Whisk together the sugar and cornstarch in a large saucepan, then mix in the milk and eggs until fully combined.
- Cook the mixture: Bring the mixture to a boil over medium heat and allow to boil for one minute. Be sure to stir constantly; I like to use a rubber spatula so I can scrape the sides and bottom of the pan well.
- Add the remaining ingredients: Once thickened, remove the mixture from the heat and stir in the butter one tablespoon at a time. Add the vanilla last.
- Strain the mixture: Place a fine-mesh strainer over a bowl and strain the warm pastry cream through it to remove any lumps.
- Cover and refrigerate: Cover the pastry cream with plastic wrap, then chill in the fridge for at least two hours before assembling the cake.
While the pastry cream is chilling you can prepare the sponge cake layers. Here’s a simple breakdown for how to make them:
- Whisk together the dry ingredients: Stir together the flour, baking powder, and salt in a large mixing bowl.
- Heat the milk and butter: In a saucepan over medium heat, bring the milk and butter to a simmer. Remove from the heat.
- Beat the eggs and sugar: In another bowl, beat the eggs and sugar for about five minutes until thick.
- Mix the batter together: Once the eggs and sugar have thickened, add the vanilla and oil. Fold the flour mixture into the egg mixture, then fold in the milk-butter mixture.
- Bake the sponge cake layers: Turn the batter into two 9-inch cake pans that have been lined with parchment paper and sprayed with non-stick spray. Bake until a toothpick inserted in the middle comes out clean. Then, let cool completely.
Once your cake layers have cooled completely and the pastry cream has thoroughly chilled, it’s time to put everything together and top it with ganache!
- Assemble the cake: If needed, level the tops of the cooled cake layers with a cake leveler or knife. Place one of the cake layers onto a cake stand. Then, pipe the pastry cream into the center. It helps to leave the outer edge uncovered by about 1-inch with the pastry cream. Once you place the second layer on top, the pastry cream will go out further towards the edges.
- Make the chocolate ganache: Add the chopped chocolate and corn syrup to a large bowl. In another bowl, microwave the heavy whipping cream for about a minute. Pour the warm cream over the chocolate and let stand, undisturbed, for two minutes. Stir the ganache in one direction until smooth, then let stand until thickened.
- Pour the ganache over the cake: I like to pour it into the center of the cake and then let it drop slightly over the edges.
- Chill the cake: It needs another one to two hours in the fridge to let the ganache finish setting up and make it easier to slice.
Do You Refrigerate Boston Cream Pie?
Yes, it must be refrigerated because it’s filled with pastry cream. If you leave the cake out for too long, the pastry cream may go bad. You may refrigerate the cake for up to 4 days in an airtight container.
Can This Recipe Be Made in Advance?
Yes, the cake layers can be made up to two days in advance. Wrap them tightly in plastic wrap and refrigerate until ready to use.
The pastry cream can also be prepared up to three days before you plan on assembling the cake. Press a piece of plastic wrap directly onto the pastry cream to prevent it from forming a skin.
- My pastry cream recipe will yield a little over two cups. I prefer to use all of it whenever I assemble the cake, but feel free to use less if you prefer!
- The corn syrup in the chocolate ganache is optional, but I highly recommend it because it makes the ganache shinier.
- Use full-fat heavy cream and milk in this recipe. All that fat helps the ganache and pastry cream set up.
More Classic Cake Recipes to Make!
Boston Cream Pie
- ½ cup granulated sugar (100 grams)
- ¼ cup cornstarch or cornflour (32 grams)
- 2 cups whole milk (480 ml)
- 4 large egg yolks
- 3 tablespoons unsalted butter sliced into tablespoon-sized pieces (45 grams)
- 2 teaspoons pure vanilla extract
- 2 cups all-purpose flour spooned & leveled (250 grams)
- 2 teaspoons baking powder
- ½ teaspoon salt
- ½ cup unsalted butter sliced and at room temperature (115 grams)
- 1 cup whole milk (240 ml)
- 4 large eggs at room temperature
- 2 cups granulated sugar (400 grams)
- 2 tablespoons vegetable or canola oil (30 ml)
- 2 teaspoons pure vanilla extract
- 4 ounces semi-sweet chocolate chopped (113 grams)
- 1 tablespoon light corn syrup (20 grams)
- ½ cup heavy whipping cream (120 ml)
- To make the pastry cream: In a large saucepan, whisk together the sugar and cornstarch until well combined. Set aside.
- In a separate large mixing bowl, whisk together the milk and egg yolks until fully combined. Slowly pour the wet ingredients into the saucepan with the sugar and cornstarch mixture and whisk until fully combined.
- Place the saucepan over medium heat and bring to a boil stirring often (I suggest using a rubber spatula to scrape around the bottom and sides of the pan a few times). Allow to boil for one minute, the mixture should be pretty thick at this point. Remove from the heat and stir in the butter, one tablespoon at a time, then stir in the vanilla extract.
- Strain the mixture through a fine-mesh strainer into a heat-proof bowl. Cover with plastic wrap, placing the plastic wrap directly on the surface of the custard, and refrigerate until chilled, about 2 hours.
- To make the sponge cake: Preheat the oven to 350°F (180°C). Lightly grease two 9-inch cake pans with nonstick cooking spray, line the bottom of the pans with parchment paper, and set aside.
- In a large mixing bowl, sift the flour, baking powder, and salt together. Set aside.
- Combine the sliced butter and milk in a large saucepan and place over medium heat, stirring occasionally. Once the mixture starts to simmer, remove it from the heat and set aside to cool slightly.
- In a separate large bowl with a handheld mixer or in the bowl of a stand mixer fitted with the whisk attachment, beat the eggs and sugar together until thick and light in color, about 5 minutes. Then, mix in the oil and vanilla extract until well combined.
- Carefully fold or mix in the dry ingredients until just combined.
- Pour the hot milk and butter mixture over the batter and gently fold it in or mix it in on low speed until just combined.
- Pour the cake batter into the two prepared pans and spread it around into one even layer.
- Bake for 25 to 30 minutes or until a toothpick inserted into the center of the cakes comes out clean.
- Allow the cakes to cool at least 20 to 30 minutes on a wire rack before flipping the pans over to remove the cakes. Set aside and allow the cake layers to cool completely.
- To assemble the cake: Once the pastry cream is thoroughly chilled and you are ready to use it, whisk it until it’s smooth. If the pastry cream is too cold, let it sit at room temperature for 15 to 20 minutes.
- Level the tops of each cake with a cake leveler or knife, if needed. Place one of the cake layers on a cake stand or a large plate.
- Pipe a border of pastry cream around the outside of the cake layer, leaving the outer 1-inch uncovered. Then, add the rest of the pastry cream into the center and spread it out into one even layer.
- Gently place the second cake layer upside-down on top of the pastry cream and lightly press it down to help spread the pastry cream filling to the edge.
- Refrigerate while you prepare the ganache.
- To make the chocolate ganache: Add the chopped chocolate and corn syrup to a large heatproof bowl. Set aside.
- Pour the heavy whipping cream into a glass measuring cup and heat in the microwave for 45 seconds to 1 minute.
- Pour the warm heavy whipping cream over the chocolate and let it sit for 2 minutes. Start stirring slowly in the middle of the bowl, and continue whisking in one direction until the mixture is smooth and well combined.
- Allow to cool slightly (about 15 to 20 minutes) or until this ganache has thickened, but is still pourable.
- Remove the cake from the refrigerator. Pour the ganache onto the center of the top of the cake and gently spread it around the top.
- Refrigerate for 1 to 2 hours to allow the ganache to firm up, then slice, and enjoy!