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Boston Cream Cupcake
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5 from 4 votes

Boston Cream Cupcakes



  • 6 tbsp butter softened
  • 3/4 cups sugar
  • 1/3 cup sour cream room temperature
  • 2 tsp vanilla extract
  • 2 large eggs room temperature
  • 1 1/4 cups all-purpose flour
  • 2 tsp baking powder
  • ¼ tsp salt
  • 1/2 cup milk room temperature


  • 2 egg yolks
  • 6 tbsp sugar
  • 1 1/2 tbsp cornstarch
  • 1 cup + 2 tbsp milk
  • 1 tbsp butter
  • 1 tsp vanilla extract


  • 1 1/2 cups semisweet chocolate chips
  • 2 tbsp light corn syrup
  • 3/4 cup heavy whipping cream



  • Preheat oven to 350°F and grease a cupcake pan or line with cupcake liners. Set aside.
  • In a large mixing bowl, cream butter and sugar together about 3-4 minutes.
  • Stir in the sour cream and vanilla until well combined.
  • Add the eggs one at a time, mixing well after each one.
  • In a separate mixing bowl, combine all of the dry ingredients for the cupcakes.
  • Add half of the dry mixture to the wet mixture and stir until combined, Mix in the milk, and then the remaining dry mixture.
  • Fill the cupcake tin about halfway.
  • Bake 15-17 minutes.
  • Let the cupcakes cool in the pan for 5 minutes and finish cooling on a cooling rack.


  • Put the egg yolks in a medium-sized bowl and gently beat them together. Set aside.
  • In a large saucepan mix together the sugar, cornstarch, and milk until smooth.
  • Heat over medium-high, stirring continuously until it starts to thicken.
  • Allow to cook and simmer 2 additional minutes and remove from heat.
  • Temper the egg yolks by whisking in 1/2 cup of the milk mixture 1 tablespoon at a time. Add the tempered egg yolks to the milk mixture.
  • Heat the mixture over medium heat, bring to a simmer and allow to cook 2 additional minutes.
  • Remove from heat, stir in the butter and vanilla, and allow to cool t room temperature.


  • Put the chocolate chips and corn syrup in a large bowl. Set aside.
  • Microwave the heavy cream in a microwave-safe dish.
  • Pour the hot cream over the chocolate chips and corn syrup.
  • Allow to sit for 5 minutes, then whisk until completely smooth.


  • Cut the tops of the cupcakes off, and scoop out a good bit of the center.
  • Transfer the filling to a piping bag and fill the center of each cupcake (or you could use a spoon, it would just be a little messier), and return the tops of the cupcakes.
  • Dip the tops of the cupcakes in the chocolate ganache.
  • Refrigerate cupcakes until ready to serve.