Boston Cream Pie
 
Prep Time
Cook Time
Total Time
 
Author:
Type of recipe: Cakes
Cuisine: American
Yield: 8-10
Ingredients
(All ingredients must be at room temperature unless otherwise noticed)
For the sponge cake:
  • 2 eggs (L), separated
  • 2 egg yolks
  • ¼ teaspoon cream of tartar
  • 2 tablespoons (30 g) unsalted butter
  • ¼ cup (60 ml) whole milk
  • 1¼ cups (250 g) caster (superfine) sugar
  • 1 teaspoon pure vanilla extract
  • 1¼ cups (125 g) cake flour (not self-rising)
  • 1¼ teaspoons baking powder
  • ½ teaspoon salt
  • 1 teaspoon lemon zest
For the filling (pastry cream):
  • 1 cup plus 2 tablespoons (250 ml) whole milk
  • 1 vanilla bean
  • ¼ cup plus 1 tablespoon (65 g) cornstarch
  • 2 egg yolks (L)
For the chocolate glaze (ganache):
  • ½ cup (120 ml) whipping cream
  • 4 oz (115 g) dark chocolate
Method
Sponge cake:
  1. Preheat oven (electric) to 350º F (175ºC) and place oven rack in the middle position.
  2. Butter two, 8-inch (20 cm Ø) round cake pans (bottom and sides). Line the bottom of both pans with parchment paper and butter the top surface of the parchment paper as well. Set aside.
  3. Separate the eggs just from the fridge —the egg whites in a large mixing bowl and the yolks in the bowl of your electric mixer (either stand or manual) fitted with the whisk—, cover both bowls with plastic wrap and let them sit on the counter to room temperature before using.
  4. Meanwhile, sift together flour, baking powder, and salt in a large bowl.
  5. Add lemon zest to the sifted dry ingredients above and mix with a whisk until totally combined. Set aside.
  6. In a small size saucepan, heat the milk and the butter over medium-low heat; stirring constantly until butter melts and being careful not to boil the milk.
  7. Remove from heat, and stir in the vanilla extract. Cover and keep warm.
  8. With an (electric) whisk, beat the egg whites at medium speed until foamy. Add the cream of tartar and continue beating until incorporated. Now, with the mixer running, gradually add ½ cup (100 g) of the sugar, one tablespoon at a time, and beat at medium-high speed until glossy, soft peaks form. Set aside.
  9. In the bowl of your stand (or hand) mixer, fitted with the whisk (or in a large mixing bowl) beat together the yolks and the remaining sugar ( ¾ cup / 150 g) at medium-high speed for 3-5 minutes until thick and fluffy.
  10. With the mixer running at medium speed, gradually pour the warm milk mixture until completely combined.
  11. With the mixer on low speed, add the dry ingredients in two batches, mixing just to incorporate after each addition.
  12. Now, using a rubber spatula or a large balloon whisk, very gently fold (do not stir) a small quantity of the foamy egg whites into the batter to lighten it. Next, fold in the remaining eggs whites in two batches just until the batter is totally combined. It is important not to over fold the batter or it will deflate. The batter will be smooth and spongy.
  13. Divide the batter evenly (you can use a kitchen scale here for higher accuracy) between the two prepared pans and smooth the top surface with an offset spatula or the back of a spoon.
  14. Bake for 25-30 minutes until the top springs back when lightly pressed, and a cake tester inserted in the center of one of the cakes comes out clean. If not, check every 2 minutes until it does.
  15. Let cool on a cooling rack inside the pans for 10 minutes.
  16. Finally, unmold the cakes and let them cool completely upside down on the cooling rack. If you have the time, once they have completely cooled, wrap each cake individually with plastic wrap and chill in the refrigerator for at least one hour (or even better, overnight); by doing this, applying both the filling and the frosting will be a lot easier, the crumb will be more settled, and the flavours will be more enhanced.
Filling (pastry cream):
  1. Start by flavouring the milk; split the bean lengthwise into two halves with a sharp knife and put it in a medium size saucepan together with the milk. Bring to a boil over medium heat. Remove from the heat, stir, and set aside.
  2. In a medium bowl, whisk together vigorously the egg yolks with the sugar for a few minutes until they foam and thicken.
  3. Add cornstarch and keep on whisking until totally combined.
  4. Gradually, pour half of the flavoured milk while whisking constantly.
  5. Once everything is totally combined, pour over the rest of the milk and heat over low heat stirring constantly just until it thickens and a few bubbles appear on the surface (please note that the mixture will thicken a bit more once it’s cold).
  6. Pour into a heatproof bowl and cover with a piece of plastic wrap pressed right up against the surface of the cream; this will prevent a skin from forming on the surface, as well as keep condensation from dripping. Set aside and chill completely before applying to the cake. After cooling, keep in the refrigerator.
Chocolate glaze (ganache):
  1. Roughly chop chocolate and place in a medium size heatproof bowl. Set aside.
  2. In a medium size saucepan, bring cream to a boil.
  3. Immediately, pour the cream over the chopped chocolate and let sit for one minute.
  4. Stir well with a rubber spatula until totally incorporated and smooth.
  5. Let sit for a few minutes before using.
Assembling the cake:
  1. If necessary (in case your cake is slightly domed), even both layer cakes using a long serrated knife or a cake leveler and brush away any excess crumbs with a pastry brush.
  2. Transfer one layer cake (bottom side facing up) to a cake stand or serving plate (the bottom layer cake will always be the one that turned out less attractive from the oven) and with an offset spatula (or a spoon) spread a generous layer of the pastry cream evenly over the cake layer to the edge.
  3. Place the second layer cake (bottom side facing up too) atop pastry cream, pressing slightly to adhere.
  4. Finally, pour the chocolate glaze on top layer of the cake and using an offset spatula generously spread it evenly, allowing some to dribble down the sides.Keep the cake refrigerated and covered (2-3 days). Serve at room temperature.Firma Rosa M Lillo
Notes
– Before beating the egg whites, make sure both the bowl and the whisk are spick-and-span, immaculately clean and dry, and free from any traces of grease.
– There shouldn’t be any traces of egg yolk in your egg whites either.
– You can also use the eggs together, without separating, avoiding the egg whites whipping process. The batter will be equally rich and moist (especially if using an electric mixer) but, in my opinion, a little less fluffy and melt-in-your-mouth than the separated-egg version.
– Remember: when assembling our cake, cakes and pastry cream should be totally cooled but chocolate glaze should be somewhat warm.
– National (USA) Boston Cream Pie day: October 23rd
Recipe by Pemberley Cup & Cakes at https://pemberleycupandcakes.com/en/2014/10/21/boston-cream-pie/