An American classic dessert, Boston Cream Pie is a moist and tender vanilla cake filled with a thick layer of rich pastry cream and draped with a glossy dark chocolate ganache. This decadent 6-inch mini Boston Cream Pie perfect for small gatherings!
Preheat the oven to 325 °F. Lightly spray two 6-inch round cake pans with baking spray, line with parchment paper, then spray the parchment. If you’re using Bake-Even strips, soak two in cold water for 5 minutes, wring them out, then wrap the pans with them tightly (you won't need to level the cakes later if you use them).
Make the cake: In the bowl of a stand mixer fitted with a paddle attachment (or a large bowl for a hand mixer), beat the sugar and eggs together at medium-high speed until lightened, about 3 to 4 minutes (batter will fall from the paddle in thick ribbons). Mix in the canola oil on low speed.
Add the flour, baking powder, and salt to the egg mixture and beat on low speed just until combined, about 1 minute. Scrape the sides of the bowl and beat again briefly to fully incorporate the flour.
Heat the milk and butter in a saucepan set over medium heat until small bubbles form and the mixture is steaming. Remove the pan from the heat and stir until the butter is fully melted. Stir in the vanilla extract.
With the mixer going on low speed, slowly add the hot milk mixture to the cake batter, mixing until the batter is well combined. Scrape the bowl and mix briefly until the batter is smooth (it will be very thin).
Wrap the cake pans with the wet Bake-Even strips. Divide the batter evenly into the prepared pans. Measuring the batter with a kitchen scale helps the accuracy.
Bake the cakes for 25 to 30 minutes, or until they're a deep golden brown and beginning to pull away from the sides of the pan. A cake tester inserted into the center should come out clean.
Remove the cakes from the oven and cool them in the pans for 10 minutes. Turn them out onto a rack to cool completely.
Make the pastry cream: In a small bowl, whisk the egg yolks briefly. Add half of the sugar and cornstarch and whisk to combine. Set aside.
Whisk together the milk and the remaining sugar in a medium saucepan. Using the tip of a sharp knife, split the vanilla bean and scrape the seeds into the milk mixture, then add the vanilla bean.
Heat the milk mixture over medium heat, stirring occasionally, until small bubbles form and it starts to steam.
Gently heat the yolk mixture by slowly adding ¼ cup of the warmed milk mixture to the yolk mixture while continuously whisking. Add another ¼ cup of the milk and whisk again. This process is called tempering the eggs, and its purpose is to prevent the yolks from curdling while the custard cooks.
Add the yolk mixture to the pan and cook, whisking constantly, until the pastry cream is bubbling and thickened. Allow it to boil approximately 1 minute longer, stirring constantly. Don't overcook the pastry cream to avoid overcooking the eggs.
Remove the pastry cream from the heat and strain through a fine mesh strainer into a clean bowl, removing the spent vanilla bean. If the custard boiled during thickening, straining it out will help remove any curdled bits of egg. Don’t toss that vanilla bean - instead rinse the bean, then place it in a jar and cover with vodka to make your own vanilla extract.
If you are using vanilla extract instead of a vanilla bean, stir it in now along with the butter. Stir until the butter melts, but don't over-mix, as this will thin the custard.
Cool the custard using an ice bath (½ ice cubes, ½ water, reaching halfway up the sides of the bowl). Stir the custard occasionally until it's cooled to room temperature (a digital thermometer should read about 80 °F).
Place a piece of plastic wrap on the surface of the custard and refrigerate until needed.
Make the ganache topping: Place the chopped chocolate in a heat-proof bowl. Heat the cream to a simmer, either on the stove in a small saucepan or in the microwave.
Pour the cream onto the chocolate, cover, and let sit for 2 to 3 minutes, then start stirring. At first it will look grainy, but keep stirring until the mixture is smooth. Add the corn syrup (if using) and vanilla and stir well.
Assemble the cake: Level the cakes (if needed). Place one of the cakes, right side up, on a cake plate. Top with the pastry cream, spreading it right to the edges (you want at least ½-inch of filling inside when the cake is assembled). Place the top layer, upside down, on the filling.
Pour the ganache over the filled cake, spreading it with a small offset spatula to the edges to spill over the sides. Let the ganache set for a few minutes before serving.
Storage instructions: Boston Cream Pie should be kept in the refrigerator, covered loosely with foil or plastic wrap. It will stay fresh for 3 to 4 days.
Make-ahead instructions: The cakes can be made a day ahead and chilled, wrapped in plastic wrap. Bring it to room temperature before assembly. The pastry cream can be kept in the refrigerator for several days, with plastic wrap pressed onto the surface. It's best to make the ganache right before assembly.
Recipe Notes
If you want an even richer pastry cream, you can substitute up to ½ cup of heavy cream for the milk.You can choose your favorite chocolate type: milk, semi sweet, or dark, depending on your preference. The best type of chocolate to use are chocolate wafers or a bar of chocolate. Candy melts (aka candy wafers, confectionery coating, compound coating, or compound chocolate) use cheaper ingredients than in pure chocolate, producing a lesser flavor profile, in my opinion. And save the chocolate chips for another day - they don't melt as smoothly.For a full-sized cake, just double all the ingredients. Bake the cake in two 9-inch round cake pans for 30 to 35 minutes. You can easily get 10 to 12 slices from the full-sized version.