Cook's Illustrated

Foolproof Sponge Cake

Published September 1, 1998.

This all-purpose recipe depends on a reliable combination of beaten yolks, whipped whites, and baking powder for lift. (Oh, and it makes a great Boston cream pie.)

The Problem

A classic sponge cake--which we feature here in a recipe for Boston cream pie--should be neither dry nor tough, though it often is, nor should it be difficult to make (yet most recipes are a challenge).

The Goal

Boston cream pie has the distinction of being called something that it is not: a pie. It is of course really a cake made with a middle layer of pastry cream and a chocolate glaze. What we wanted to do was to perfect the cake part of this "pie." We wanted a fairly light cake, one with a springy but delicate texture that could stand up nicely to a rich custard filling and a sweet chocolate glaze. We wanted a basic building-block cake recipe, just as dependable and useful as a classic American layer cake, another popular choice for Boston cream pie.

The Solution

We decided to go with a hot milk sponge cake, which differs from a génoise only in that little or no fat is added and some or all of the egg whites are beaten separately, which delivers a more stable batter and thus a more foolproof recipe. The sponge cake worked. After fine-tuning a "classic" recipe--adding butter for flavor and to tenderize the crumb, separating fewer of the eggs to correct an overly light structure, and substituting some all-purpose flour for the cake flour we had been using to provide more body--we had the cake we wanted. The rest was just icing on the cake--as well as some pastry cream filling.

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