Boston cream pie is a yellow buttery sponge cake with creamy custard filling this is topped with a fudgy chocolate ganache glaze. This recipe keeps it easy, using a cake mix for simplicity, but with a quick technique that keeps the sponge cake texture.
The History of Boston Cream Pie
Why is it called pie when it is a cake? That is the million-dollar question! Apparently, back in the mid-1800s when it was invented, pie plates were the most common cooking vessel. These cakes were originally baked in pie plates, and thus called "pie." Boston cream pie was named the official state dessert of Massachusetts in 1996. If you want to know more about iconic Massachusetts food, take a look at our state dinner post.
How Do You Make Boston Cream Pie?
There are three simple components to this cake:
- Cream Filling
- Sponge Cake
- Chocolate Ganache Frosting
Step One: Make the Cream Filling
- We start with making the cream filling because it takes a while to cool.
- Combine the egg yolk, sugar, and cornstarch together. It will look a little bit like cooked egg yolk.
- Add this yolk mixture and the half and half to a saucepan and cook on medium-low heat for 5 minutes. Raise the temperature and let it boil for one minute.
- Remove the pan from the stove and whisk in butter and vanilla.
Step Two: Refrigerate the Cream Custard
- The custard should be nice and thick, but it will continue to thicken as it cools.
- Transfer the custard into a bowl. Place a piece of plastic wrap over the top of the the custard and press along the top, as well as on the sides of the bowl, to remove any air pockets. The plastic wrap should be directly along the surface of the custard. This keeps a film from forming on the top of the custard.
- Refrigerate for at least 2 hours. This can be made a day ahead and stored in the refrigerator.
Step Three: Beat Egg Whites for the Cake
- This recipe takes the easy route to a buttery sponge cake and uses a cake mix. To get that sponge-like texture, we whip up the egg whites separate from the yolks. Beat them on high speed with a whisk attachment until they form stiff peaks.
- To test if they are stiff, use a spoon or your whisk attachment to scoop into the egg whites. If it leaves a crevice and a peak that stands tall, it is ready. If the peak starts to droop, beat it some more.
Step Four: Mix Cake Ingredients
- Put all of the cake ingredients, except for the egg whites, into a large mixing bowl and beat for two minutes.
- Gently fold in the egg whites. To fold in the egg whites, use a large spatula, and cut into the egg whites, scooping the spatula under the batter mixture, then turn over onto the egg whites. Do this softly so that you keep the texture of the egg whites.
- You will end up with a batter that has lots of little air bubbles, and little pockets of egg whites. All of the egg white should be incorporated throughout the batter.
- Line cake pans with parchment paper and spray the paper and pans with nonstick spray. Bake until a toothpick comes out clean.
- Cool completely before assembling.
Step Five: Begin Assembling the Cake
- Place one layer of the cake onto a cake plate or serving platter.
- Spoon the custard filling over the top of the cake, to the ends. You may have as much as a half cup of custard left over.
Step Six: Make the Ganache
- It is best to make the ganache right before pouring over the cake. It should pour easily onto the cake, only requiring a little guidance from your spatula to coat the top of the cake and begin falling down the sides.
- Place the cream, corn syrup, and chocolate in a saucepan over medium heat. Stir continuously until the chocolate is melted.
*Note: I normally love dark chocolate, but prefer semi-sweet chocolate for this recipe. Use the baking squares, not chips. Chocolate chips are designed to hold their shape in baking, so the squares melt much better.
- Remove from heat and stir in vanilla.
- Place the second cake layer on top of the filling.
- Pour ganache over the top. Spread gently to the cake edges.
Tips and FAQs
Corn syrup gives the ganache the classic Boston Cream Pie shine. It is gorgeous, but if you don't want to use corn syrup you can substitute honey. While not exactly the same, it still gives a little gloss. You could also leave the corn syrup out entirely. It is not necessary for the flavor of the ganache.
Some small lumps in the custard is normal. If you want a completely smooth custard, strain it using a fine-mesh sieve.
Because of the custard filling, Boston Cream Pie does need to be refrigerated. Wrapped tightly, it will last in the refrigerator for up to 5 days.
Both the custard and the filling can be made up to 2 days in advance. The ganache should be made right before assembling. If you want the entire cake made and assembled in advance you can do that up to 24 hours ahead.
Related Recipes and Links
More Massachusetts Recipes:
More Chocolate Recipes:
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Boston Cream PieRecipe by:
- 4 egg yolks
- ¾ cup sugar
- 4 tablespoons cornstarch
- 2 cups half and half
- ¼ cup butter, cut into 1-inch pieces
- 2 teaspoons vanilla extract
- 1 yellow cake mix
- 4 eggs, separated
- 1 cup milk
- ½ cup butter, cooled
- 1 package (3.4 ounce) vanilla instant pudding
Chocolate Ganache Glaze
- ½ cup heavy cream
- 2 tablespoons corn syrup
- 4 ounces semisweet baking chocolate Use baking squares, not chocolate chips, for best results
- ½ teaspoon vanilla extract
Making the Custard
- Separate eggs and store egg whites for another use.In a small bowl, mix egg yolks with sugar and cornstarch.
- Add egg yolk mixture and half and half to a medium saucepan. Heat over medium-low heat for 5 minutes.Increase heat until it begins bubbling. Let it bubble for 1 minute.
- Remove pan from heat and whisk in butter and vanilla.
- Pour into a bowl. Cover tightly with plastic wrap, pressing the plastic wrap directly against the custard. Refrigerate for at least 2 hours.
Making the Cake
- Preheat oven to 350 degrees. Spray two 9-inch cake pans with nonstick spray. Line with parchment circles and spray the parchment as well.
- Separate egg whites from egg yolk. Save egg yolk for later in the recipe.Place egg whites in a mixing bowl. Using the whisk attachment of your stand or hand mixer, beat on high speed for several minutes, until stiff peaks form. (See notes under step 3 of the blog for tips on how to know if you have stiff peaks.)
- In a separate bowl, mix together cake mix, egg yolks, milk, butter, and pudding mix and beat for 2 minutes.Gently fold in egg whites.
- Evenly pour batter into the cake pans. Bake 25-28 minutes, or until a toothpick inserted comes out clean.Cool for 5 minutes. Remove the cake from pans and cool completely.
Making the Chocolate Ganache Frosting
- Heat cream, corn syrup, and chocolate in a small saucepan over medium heat. Stir continuously until the chocolate is completely melted. Remove pan from heat and stir in vanilla. Use immediately.
Assembling the Cake
- Place one layer of cake onto a cake plate or serving platter.Spread the custard over the top of the cake layer, spreading to the edges.Place the second cake layer on top of the custard.Pour the ganache onto the center of the top cake layer. Once all of the ganache has been poured onto the cake, use a spatula to spread to the edges. Allow some of the ganache to drip down the sides.
- Refrigerate the cake for at least 2 hours before serving. This can be made up to 24 hours in advance.