Published March 1, 2011. From Cook's Illustrated.
Why this recipe works:
A hot-milk sponge cake made a good base in our Boston Cream Pie recipe because it didn’t require any finicky folding or separating of eggs. Baking the batter in two pans eliminated the need to slice a single cake horizontally before adding the...(more)
A hot-milk sponge cake made a good base in our Boston Cream Pie recipe because it didn’t require any finicky folding or separating of eggs. Baking the batter in two pans eliminated the need to slice a single cake horizontally before adding the...(more)
Serves 8 to 10
Chill the assembled cake for at least 3 hours to make it easy to cut and serve.Ingredients
- Pastry Cream
- 2 cups half-and-half
- 6 large egg yolks
- 1/2 cup (3 1/2 ounces) sugar
- pinch table salt
- 1/4 cup unbleached all-purpose flour
- 4 tablespoons cold unsalted butter, cut into four pieces
- 1 1/2 teaspoons vanilla extract
- Cake
- 1 1/2 cups (7 1/2 ounces) unbleached all-purpose flour
- 1 1/2 teaspoons baking powder
- 3/4 teaspoon table salt
- 3/4 cup whole milk
- 6 tablespoons (3/4 stick) unsalted butter
- 1 1/2 teaspoons vanilla extract
- 3 large eggs
- 1 1/2 cups (10 1/2 ounces) sugar
- Glaze
- 1/2 cup heavy cream
- 2 tablespoons light corn syrup
- 4 ounces bittersweet
chocolate, chopped fine
Instructions
- 1. For the Pastry Cream: Heat half-and-half
in medium saucepan over medium heat until just simmering. Meanwhile,
whisk yolks, sugar, and salt in medium bowl until smooth. Add flour
to yolk mixture and whisk until incorporated. Remove half-and-half
from heat and, whisking constantly, slowly add ½ cup to yolk
mixture to temper. Whisking constantly, return tempered yolk mixture
to half-and-half in saucepan.
- 2. Return saucepan to medium heat and cook,
whisking constantly, until mixture thickens slightly, about 1
minute. Reduce heat to medium-low and continue to simmer, whisking
constantly, 8 minutes.
- 3. Increase heat to medium and cook,
whisking vigorously, until bubbles burst on surface, 1 to 2 minutes.
Remove saucepan from heat; whisk in butter and vanilla until butter
is melted and incorporated. Strain pastry cream through fine-mesh
strainer set over medium bowl. Press lightly greased parchment paper
directly on surface and refrigerate until set, at least 2 hours and
up to 24 hours.
- 4. For the Cake: Adjust oven rack to middle
position and heat oven to 325 degrees. Lightly grease two 9-inch
round cake pans with nonstick cooking spray and line with parchment.
Whisk flour, baking powder, and salt together in medium bowl. Heat
milk and butter in small saucepan over low heat until butter is
melted. Remove from heat, add vanilla, and cover to keep warm.
- 5. In stand mixer fitted with whisk
attachment, whip eggs and sugar at high speed until light and airy,
about 5 minutes. Remove mixer bowl from stand. Add hot milk mixture
and whisk by hand until incorporated. Add dry ingredients and whisk
until incorporated.
- 6. Working quickly, divide batter evenly
between prepared pans. Bake until tops are light brown and toothpick
inserted in center of cakes comes out clean, 20 to 22 minutes.
- 7. Transfer cakes to wire rack and cool
-completely in pan, about 2 hours. Run small plastic knife around
edge of pans, then invert cakes onto wire rack. Carefully remove
parchment, then reinvert cakes.
- 8. To Assemble: Place one cake round on
large plate. Whisk pastry cream briefly, then spoon onto center of
cake. Using offset spatula, spread evenly to cake edge. Place second
layer on pastry cream, bottom side up, making sure layers line up
properly. Press lightly on top of cake to level. Refrigerate cake
while preparing glaze.
- 9. For the Glaze: Bring cream and corn syrup
to simmer in small saucepan over medium heat. Remove from heat and
add chocolate. Whisk gently until smooth, 30 seconds. Let stand,
whisking occasionally, until thickened slightly, about 5 minutes.
- 10. Pour glaze onto center of cake. Use
offset spatula to spread glaze to edge of cake, letting excess drip
decoratively down sides. Chill finished cake 3 hours before slicing.
Cake may be made up to 24 hours before serving.
Step-by-Step
For the Best Pie, Ditch TraditionWe deconstructed the recipe for Boston Cream Pie invented by the Parker House hotel—and found it needed a complete overhaul.
- DULL, HARD GLAZEThe original glaze dries to a hard, dull-looking shell that won’t bond with the cake. And who really wants brittle piped frosting on top?
OVERLY LEAN, SWEET CAKE
The traditional sponge cake is too lean and sweet for modern tastes. And if you don’t know what you’re doing, it will bake up flat instead of airy.
- RUNNY FILLINGIt’s all too easy to create a pastry cream that’s too thin, leading to a filling that dribbles down the cake.
Step-by-Step
Thickener Face-Off: Flour vs. CornstarchWhen developing the pastry cream filling for our Boston Cream Pie, too often we found that the custard, which is made by heating half-and-half with egg yolks and cornstarch, failed to thicken properly. Would flour be more reliable?
THE EXPERIMENT
We made multiple batches of pastry cream thickened with 3 tablespoons of cornstarch according to our recipe, and another set thickened with 4 tablespoons of flour (a less potent thickener than cornstarch) that we cooked longer to remove the floury taste.
THE RESULTS
The flour-thickened batches of pastry cream set up and held perfectly every time, while those containing cornstarch occasionally did not set at all or even thinned out once they had thickened.
THE EXPLANATION
When starch is heated in water, its granules absorb water, swell, and eventually burst, leaking a starch molecule called amylose that diffuses throughout the solution, trapping additional water and forming a coherent network, or gel. Because cornstarch is a pure starch, it has far more amylose than flour (which is only about 75 percent starch), giving it maximum thickening power. But its purity makes cornstarch finicky. If a custard such as pastry cream isn’t heated high enough, an enzyme in the yolks called amylase can weaken the starch gels so the custard never fully sets up. And even if it does thicken properly, overwhisking the mixture can break the bonds of the starch gels and thin it out. Flour, on the other hand, contains proteins and lipids that dilute its capacity to form starch gels, so that more of it is needed for thickening. But these non-starch components also act as binders, keeping water trapped and ensuring that a liquid not only thickens, but stays that way.
