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Boston cream pie on a marble and wood cake stand.

High Altitude Boston Cream Pie

Heather Smoke
A classic Boston cream pie, with layers of buttery yellow cake, vanilla bean custard, and chocolate ganache.

All recipes on Curly Girl Kitchen are developed for high altitude at 5,280 feet.

5 from 1 vote
Prep Time 1 hr
Cook Time 25 mins
Total Time 1 hr 25 mins
Course Dessert
Cuisine American
Servings10

Equipment

  • 2 6-inch Round Cake Pans (3 inches deep)
  • Saucepan + Whisk

Ingredients
 

Cake

  • 6 tbsp unsalted butter, melted
  • 2 tbsp vegetable oil
  • 1 cup granulated sugar
  • 2 large eggs
  • 1 tsp vanilla extract
  • cup whole buttermilk
  • cup full-fat sour cream
  • 1 ½ cups cake flour, spooned and leveled
  • 1 ¾ tsp baking powder
  • ½ tsp coarse Kosher salt (if using table salt, use half the amount)

Custard

  • cup granulated sugar
  • 3 tbsp corn starch
  • 1 cup whole milk
  • 3 large egg yolks
  • 1 tsp vanilla bean paste (or the seeds scraped from 1 vanilla bean)
  • 2 tbsp unsalted butter

Ganache

  • 2 oz semi sweet or dark chocolate, finely chopped
  • 1 ½ oz heavy whipping cream

Instructions
 

Cake

  • Preheat the oven to 350 F, and spray the bottoms of two 6-inch cake pans with non-stick baking spray.
    TIP: It's best if your pans are 3 inches deep, as there's almost too much batter to bake in 6 inch pans that are only 2 inches deep. The shallower pans will still work (it's what I used), but the top of the cake will brown a little bit more than if you use deeper pans.
  • In a large bowl, whisk together the melted butter, oil, sugar, eggs, vanilla, buttermilk and sour cream, until smooth.
  • In a separate bowl, sift together the flour, baking powder and salt. Add the dry ingredients to the wet, and whisk for 10-15 seconds until smooth and well combined.
  • Divide the batter between the pans. Bake on the center oven rack for about 25-27 minutes, until a cake tester comes out clean.
  • Set the pans on a cooling rack, cover loosely with a clean kitchen towel, and cool completely before assembling your cake.

Custard

  • When your cakes are cool, and you're ready to assemble the cake, you can make the pastry cream.
  • In a saucepan, whisk together the sugar and corn starch. Slowly whisk in the milk, then the egg yolks, until smooth.
  • Cook the custard over medium heat, whisking constantly. As the custard starts to thicken, it may seem lumpy or curdled at first, but just keep whisking and it will smooth out. When the custard has thickened, continue to cook and whisk for 1 minute, to fully activate the corn starch. This whole process should take about 8-10 minutes.
  • Remove from the heat and vigorously whisk in the vanilla and butter until smooth. The custard will be thick, and you don't need to wait long for it to cool to assemble your cake.
    TIP: If the custard seems too thick for your liking, you can whisk in some cold milk or cream, 1 tablespoon at a time, whisking vigorously until smooth. If the custard is too soft, though, it won't be able to support the weight of the top cake layer.
  • Remove the cakes from the pans, and set one cake on a cake plate or pedestal. Spread the warm custard in an even layer over the cake, stopping at the edges, or fill a piping bag with the custard and pipe it onto the cake.
  • Set the second cake on top of the custard, and gently press it down a little, but not so much that you squish the custard out the sides.

Ganache

  • Finely chop the chocolate, scrape into a bowl, and set aside.
  • Warm the cream in the microwave or in a saucepan on the stove, just until it begins to simmer around the edges.
  • Pour the hot cream over the chocolate and stir until smooth and shiny.
  • Let the ganache cool at room temperature for 10-20 minutes, stirring occasionally, until it's thick enough that it won't run off the top of the cake. Pour the ganache over the cake, gently spreading it towards the edges so it just starts to drip over the edges, but doesn't run down the sides of the cake.
  • You can serve the cake immediately, or let the ganache set for about 30 minutes first.

Notes

Store leftover cake in an airtight container in the refrigerator for up to 2 days.
Keyword Boston, Cake, Chocolate Ganache, Cream Pie, Custard
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