Sift half a pound of flour,* and powder a pound of the best loaf-sugar. Grate the yellow rind and squeeze into a saucer the juice of three lemons. Beat twelve eggs; and when they are as light as possible, beat into them gradually and very hard the sugar, adding the lemon, and beating the whole for a long time. Then by degrees, stir in the flour slowly and lightly; for if the flour is stirred hard and fast into sponge cake, it will make it porous and tough. Have ready buttered, a sufficient number of little square tins, (the thinner they are the better,) half fill them with the mixture; grate loaf-sugar over the top of each; put them immediately into a quick oven, and bake them about ten minutes; taking out one to try when you think they are done. Spread them on an inverted sieve to cool. When baked in small square cakes, they are generally called Naples biscuits.
* Sponge cake may be made with rice flour.
If you are willing to take the trouble, they will bake much nicer in little square paper cases, which you must make of thick letter paper, turning up the sides all round, and pasting together or sewing up the corners.
If you bake the mixture in one large cake, (which is not advisable unless you have had much practice in baking,) put it into a buttered tin pan or mould, and set it directly into a hot Dutch oven, as it will fall and become heavy if allowed to stand. Keep plenty of live coals on the top, and under the bottom till the cake has risen very high, and is of a fine colour; then diminish the fire, and keep it moderate till the cake is done. It will take about an hour. When cool, ice it; adding a little lemon juice or extract of roses to the icing. Sponge cake is best the day it is baked.
Diet Bread is a foolish name for Sponge Cake.