Blueberry Cake
3 eggs 1/3 cup hot water 1 cup sugar 1 3/4 cups pastry flour 1 1/2 cups fresh blueberries sprinkled with flour Put together in the same manner as the Plain Cake, folding the blueberries in last.
This is a hot-water sponge, not a butter cake: the lift comes from well-beaten eggs, so the mixing method matters more than anything else here. The instruction to follow "the Plain Cake" means the eggs and sugar are beaten to a thick, pale ribbon before the hot water and flour go in.
- Beat the eggs properlyWith no butter and no chemical leavening listed, the volume is entirely in the eggs. Beat whole eggs with the sugar for a good five minutes with a mixer, until the batter falls in a thick ribbon and holds a trace on the surface.
- Hot water, added warmThe 1/3 cup of hot water thins the foam so the flour can be folded in without knocking out the air. Add it in a slow stream while beating, then fold the flour in by hand in two or three additions.
- Pastry flourPastry flour is softer than all-purpose. Substitute cake flour straight across, or use all-purpose with 2 tablespoons per cup replaced by cornstarch.
- Flouring the berriesTossing the blueberries in a spoonful of flour keeps them suspended rather than sinking to the bottom. Shake off the excess in a sieve or the crumb around each berry turns gluey.
- Folding in lastFold the berries with a spatula in as few strokes as possible. Overworking bursts them, and the juice will streak grey-green through the batter.
- Pan and ovenThe recipe gives no oven setting; 350F suits a sponge of this kind. An 8- or 9-inch square pan, greased and floured, takes 30 to 35 minutes; a tester in the centre should come out clean and the top should spring back.
- Frozen berriesThe recipe calls for fresh, but if using frozen, do not thaw. Toss them in flour while still hard and fold them in frozen, adding a few minutes to the bake.
- YieldOne 8- or 9-inch square cake, nine generous squares. Best the day it is baked; a sponge with no fat stales quickly.
Hot-water sponge cakes appeared widely in American cookery books in the decades either side of 1900, valued because they used no butter and kept the ingredient list to eggs, sugar, flour and water. Books of this kind often gave one "Plain Cake" method and then a run of variations that pointed back to it, which is why this entry reads as a list of proportions rather than a set of directions. Blueberries were a natural summer addition in the northeastern United States, where they were gathered wild well into the twentieth century before cultivated highbush varieties became widespread; dusting them with flour to stop them sinking is a long-standing fix and still the usual one.