Boston Cream Pie/Cake

Custard Filling:

3 large egg yolks

1/4 cup (or 50 grams) granulated sugar

2 tablespoons (or 15 grams) cornstarch

1 cup whole milk

1 tablespoon unsalted butter

1 teaspoon vanilla extract

1/4 cup heavy cream

In a medium bowl, whisk together the yolks, sugar, and cornstarch; set aside.

In a medium saucepan, bring the milk to a gentle boil.  Remove the pan from the heat and whisk about 1/3 cup of the hot milk into the yolk mixture.  Return the entire mixture to the saucepan, place over medium-high heat, and bring to a boil, whisking constantly.  Continue to boil, whisking constantly, for 1 minute.  Remove the pan from the heat, scrape the bottom of the pan with a spatula, and whisk until smooth.  Whisk in the butter until melted.

Immediately strain the custard through a fine-mesh sieve into a medium bowl.  Whisk in the vanilla extract or paste.  Cover the surface of the custard with plastic wrap, and let cool to room temperature, then refrigerate for 2 hours, or until well-chilled.

Hot Milk Sponge Cake:

1 1/3 cups (or 133 grams) sifted cake flour

1 1/4 teaspoons baking powder

1/4 teaspoon salt

1/2 cup whole milk

4 tablespoons unsalted butter, cut into tablespoons

3 large eggs, at room temperature

3/4 cup (or 150 grams) granulated sugar

1 teaspoon vanilla

Position a rack in the center of the oven, and heat the oven to 350° F.  Grease the bottom and sides of a 9-inch cake pan.  Dust the pan with flour.

Sift together, twice, the cake flour, baking powder, and salt.  Set aside.

In a small saucepan, combine the milk and butter and heat over medium heat just until the butter is melted.  Remove the pan from the heat and set aside.

In the bowl of an electric mixer, using the whisk attachment, beat the eggs at high speed until blended, about 1 minute.  Gradually add the sugar and vanilla extract and beat until pale and tripled in volume, about 6 minutes.

Sift one-third of the flour mixture over the egg mixture and gently fold it in with a rubber spatula.  Repeat with the remaining flour mixture in two more additions.

Reheat the milk mixture to just under a boil.  Add it all at once to the egg mixture and gently fold it in, making sure it is completely combined.  Scrape the batter into the prepared pan.

Bake the cake for 20 to 25 minutes, until it springs back when lightly touched and a cake tester inserted into the center comes out clean.  Cool the cake in the pan on a wire rack for 10 minutes. 

Run a paring knife around the edge of the pan and invert the cake onto the wire rack.  Reinvert the cake, so that it is right side up, and cool completely.

Bittersweet Chocolate Glaze:

3 ounces (or 85 grams) bittersweet chocolate, coarsely chopped

1/3 cup heavy cream

1/2 teaspoon vanilla extract

1/4 cup heavy cream (reserve to add in assembly stage)

Finely chop the chocolate with knife or food processor. 

In a small saucepan, bring the cream to a boil.  Remove from the heat and add the chocolate to the pan.  Stir until the chocolate is completely melted and the glaze is smooth.  Stir in the vanilla extract.  Transfer the glaze to a small bowl.  Cover the surface of the glaze with a piece of plastic wrap and let cool for about 10 minutes before using.

Assemble the cake:

Using a long serrated knife, cut the cake horizontally in half to make 2 layers.

Transfer the custard filling to the bowl of an electric mixer.  Add the reserved 1/4 cup heavy cream and, using the whisk attachment, beat the mixture at high speed until it is light and forms soft peaks, about 1 minute.

Save the smooth bottom layer for the top of the cake, and place the remaining cake layer cut side up on a serving plate.  Scrape the filling onto the layer and, using a small offset metal spatula, spread it into an ever layer.  Top with the other cake layer, cut side down.

Pour the warm chocolate glaze over the top of the cake, allowing some of it to drizzle down the sides.  Serve the cake immediately, or refrigerate.

(Store in the refrigerator in a covered container for up to a day; bring to room temperature before serving.)

Makes one 9-inch cake, serving 10.

From The Cake Book by Tish Boyle