High Altitude Boston Cream Pie
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. See FAQs for adjusting to higher or lower elevations.
Equipment
- 8-inch round cake pans (x2)
Ingredients
Cake
- 1 ½ cups cake flour, fluffed, spooned and leveled
- 1 cup granulated sugar
- 1 ¼ tsp baking powder
- ½ tsp coarse Kosher salt (if using table salt, use half the amount)
- ⅔ cup whole milk
- ⅓ cup full-fat sour cream
- 2 large eggs
- 6 tbsp unsalted butter, melted
- 2 tbsp vegetable oil
- 1 tsp vanilla extract
Custard
- ⅓ 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
- 3 ½ oz semi sweet or dark chocolate, finely chopped
- 3 oz heavy whipping cream
Instructions
Cake
- Preheat the oven to 350 F, position a rack in the center of the oven, and spray the bottoms of two 8-inch round cake pans with non-stick baking spray.
- In a bowl, sift together the flour, sugar, baking powder, and salt.
- Add the milk, sour cream, eggs, melted butter, oil, and vanilla, and whisk until smooth.
- Divide the batter between the pans. Bake on the center oven rack for about 20-25 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
- 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. Cover and refrigerate the custard until your cakes are cool, and you're ready to assemble your cake. Use a spoon to stir the custard to loosen it up and smooth out the texture, before filling 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. Be careful with thinning it out, though: if the custard is too soft, it won't be able to support the weight of the top cake layer, without squishing out.
- Remove the cakes from the pans, and set one cake on a cake plate or pedestal. To keep the cakes moist, since this is a naked cake, I like to brush the baked cakes with several tablespoons of milk.
- Spread the 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 3 ounces into a bowl, and set aside. You can also use chocolate chips, instead of chopped chocolate. (Reserve 1/2 ounce of the chopped chocolate for decorating.)
- 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.
- If your ganache is thin and runny, let it 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.
- Let the ganache cool and set for a few minutes, then sprinkle with the remaining 1/2 ounce of chopped chocolate.
- You can serve the cake immediately, or let the ganache set for about 30 minutes first.
Video
Notes
- Store leftover cake in an airtight container in the refrigerator for up to 2 days. Let the leftover cake warm up to room temperature before serving.
- Naked cakes tend to dry out more quickly, simply because they lack the layer of buttercream around the edges which keeps in moisture. I like to brush the baked and cooled cakes with two tbsp of milk (on each cake) to add extra moisture, as I assemble the layers.
- My favorite way to eat this cake when it's leftover, is to pour 2 tablespoons of milk over a slice of cake (sort of like a tres-leches cake, which is soaked in lots of milk). Then I'll warm it in the microwave for about 45 seconds at 50% power. This will soften and moisten the cake and custard, and slightly melt the ganache, and it's just so incredibly delicious like this.
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