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Overhead shot of a Boston cream pie cupcake cut in half stuffed with pastry cream and a finger dipping into the cream, next to 4 others topped with chocolate and vanilla swirled buttercream and chocolate sprinkles.

Boston Cream Pie Filled Cupcakes


  • Author: Niki
  • Prep Time: 25 minutes
  • Cook Time: 40 minutes
  • Total Time: 1 hour and 5 minutes
  • Yield: 12 Cupcakes 1x

Description

Boston cream pie cupcakes stuffed with sweet pastry cream and topped with rich chocolate buttercream will satisfy your cream filled cupcake cravings!


Scale

Ingredients

For the Pastry Cream (from The Fearless Baker by Erin McDowell):

  • 726 g (3 cups) whole milk
  • 1 g (¼ tsp) kosher salt
  • 149 g (¾ cup) granulated sugar
  • ½ vanilla bean split lengthwise
  • 135 g (about 5) large egg yolks, room temperature
  • 38 g (⅓ cup) cornstarch
  • 43 g (3 tbsp) unsalted butter, room temperature

For the Chocolate Swiss Meringue Buttercream:

  • 115 g egg whites (about 4 eggs)
  • 225 g granulated sugar
  • 340 g unsalted butter at room temperature
  • 12 g vanilla extract
  • ⅛ tsp kosher salt
  • 10 oz semi-sweet chocolate chips

To Assemble the Cupcakes:

  • 12 vanilla cupcakes (homemade, pre-made, or boxed) *See Note
  • 1 serving Chocolate Swiss Meringue Buttercream
  • 1 serving Pastry Cream
  • Chocolate Sprinkles for garnish (optional)

Instructions

For the Pastry Cream:

  1. In a medium saucepan, combine 50 g (¼ cup) sugar, milk, and salt. Scrape the seeds from the vanilla bean; add the seeds and bean to the mixture. Turn on the heat to medium and bring to a simmer.
  2. In a separate medium glass heat-proof bowl, lightly whisk the egg yolks. Slowly whisk in the remaining sugar and cornstarch; whisk until mixture pales in color and the texture is fluffy. *See note
  3. Once the milk simmers, carefully remove the vanilla bean and turn the heat down to medium low. *See note
  4. Temper the egg yolks with warm milk. Add about ¾ cup of warm milk to a heatproof measuring cup. Slowly pour the reserved milk into the egg yolks, whisking constantly. *See note
  5. Pour the tempered egg yolks into the saucepan with the remaining milk, whisking constantly. 
  6. Cook the mixture for 3-5 minutes, scraping the saucepan frequently with a silicone spatula so the mixture doesn’t stick. 
  7. Remove from heat when the mixture becomes very thick and coats the back of a spoon. Stir in butter until completed melted and incorporated. 
  8. Using a fine mesh strainer, strain the pastry cream in a shallow heat proof glass dish. Cover with plastic wrap, making sure the plastic wrap touches the surface of the pastry cream. *See note
  9. Refrigerate for a minimum of 2 hours to thoroughly chill before using. Store for up to a week in an airtight container in the fridge.

For the Chocolate Buttercream:

  1. In a large heat-proof bowl, whisk the egg whites and sugar.
  2. Heat the mixture over a double boiler, whisking constantly. Heat the mixture to 160 degrees Fahrenheit. If you don’t have a thermometer, carefully test the mixture by rubbing a small amount between your fingers. If the mixture feels gritty, continue to cook until it feels smooth. For me, this took about 10 minutes.
  3. Transfer the mixture to a stand mixer, and whip on high speed until soft peaks form and the mixture is glossy.
  4. Add in the vanilla and salt.
  5. With the mixer on high speed, gradually add in small pats of butter. All the butter to fully incorporate before adding in more butter. Continue until all the butter has been used, and the mixture is light and fluffy.
  6. Meanwhile, melt the chocolate with ¼ cup of water. Cool to room temperature. *See note
  7. Mix the cooled, melted chocolate into the buttercream.
  8. Use immediately or store in an airtight container in the fridge for up to a week.

To Assemble the Cupcakes:

  1. Before assembling the cupcakes, make sure the pastry cream and cupcakes are completely cooled. If you made the buttercream ahead, let sit at room temperature for at least an hour. *See note
  2. Using a small round cookie cutter or a spoon, hollow out a small hole in the middle of the cupcakes. The hole should go up to ¾ of the way into the cupcake.
  3. Fill each hole with pastry cream. The amount you use will depend on the size of the hole. Fill only to the top of the cupcake; do not overfill.
  4. Add the buttercream to a piping bag fitted with a star tip (or any tip of your choice). Lightly grasp the bottom of the bag with your left hand, while placing your right hand at the top of the bag. Lightly squeeze the bag with your right hand and pipe the buttercream onto each cupcake in a circular motion.
  5. Decorate with chocolate sprinkles.
  6. Repeat steps 2 through 5 for the remaining cupcakes.
  7. Serve immediately or store in an airtight container in the fridge for up to a week. *See note

Notes

For the Pastry Cream:

  • Whisk slowly when adding the sugar and cornstarch to the egg yolks to make sure the ingredients incorporate properly into the egg yolks. The mixture should turn a pale yellow and the texture will appear fluffy.
  • I like to save my used vanilla beans. Set the used bean aside to dry thoroughly then add it to sugar to make vanilla sugar, or to a bottle with vodka to make vanilla extract.
  • If we added the whisked egg yolks directly to the warm milk without tempering, we would end up with scrambled eggs. By reserving a small amount of warm milk to whisk into the eggs, we are bringing the eggs up to the temperature of the milk and preventing them from scrambling. Whisk the reserved milk slowly; mixing too quickly can result in scrambled eggs. 
  • If you do see a few bits of egg after tempering, don’t worry, we will strain those out at the end. 
  • Make sure the pastry wrap touches the top of the pastry cream. This will prevent that dreaded skin from developing on top of the pastry cream.

For the Chocolate Buttercream:

  • Make sure the melted chocolate is cool prior to adding to the buttercream. If it is too warm, the buttercream will melt and become soupy. Don’t panic if this happens; just chill the bowl of buttercream in 10 minutes intervals and re-whip to return to the correct consistency.

To Assemble the Cupcakes:

  • If you are making cupcakes from the Serious Eats recipe, I cut the recipe in half to yield 12 cupcakes. 
  • If the pastry cream or cupcakes are too warm, the buttercream will melt. If the buttercream was stored in the fridge and not brought up to room temperature prior to using, it will be very stiff and difficult to pipe.
  • If you store the cupcakes in the fridge, let them sit on the counter at room temperature for 10 to 15 minutes prior to serving.
  • Category: Desserts
  • Cuisine: American

Keywords: Cream filled cupcakes, boston cream pie, filled cupcakes, chocolate buttercream, vanilla cupcakes, pastry cream, boston cream pie cupcakes