Place the white of an egg in a bowl or plate. Add a little lemon-juice or other flavoring, and a few drops of water. Stir in powdered sugar until it is of the right consistency to spread. While the cake is still warm pile the icing on the center of the cake, and with a wet knife smooth it over the top and sides of the cake. It will settle into a smooth and glossy surface. If the icing is prepared before the cake is ready, cover it with a wet cloth, as it quickly hardens. If it becomes too stiff add a few drops of water, and stir it again. Color and flavor as desired. One egg will take about a cupful of sugar, and will make enough icing to cover one cake. If a little more is needed add a little water to the egg, and it will then take more sugar. When icing is wanted for decorating a cake, beat the whites to a froth, then beat in the sugar instead of stirring it, and continue to beat until it is firm enough to hold its form. Stirring more sugar into the unwhipped whites will make it firm enough for decorating, but the whipped icing is better. Put it into a pastry-bag with small tube, or into a paper funnel, and press it through into any shapes desired. A good icing is made of milk and sugar alone.
ROYAL ICING WITH CONFECTIONER’S SUGAR
Make this icing the same as the other, using confectioner’s sugar, which is finer than the powdered sugar, and use a little water with the egg. This makes a soft, creamy icing; the more water used, the softer it will be. If beaten instead of stirred it will become firm enough to hold in place without so much sugar being used, but in this way it dries sooner and is not so creamy. This is a good icing for layer cakes, fancy cakes, and éclairs.
BOILED ICING No. 1
Put a cupful of sugar into a saucepan with one quarter cupful of boiling water and a half saltspoonful of cream of tartar; stir till dissolved, then let it boil without stirring until it threads when dropped from the spoon. Turn it in a fine stream onto the white of one egg whipped to a stiff froth. Beat the egg until the mixture becomes smooth and stiff enough to spread, but do not let it get too cold. Pour it over the cake.
BOILED ICING No. 2
Boil sugar as directed above to the soft ball; then remove from the fire, add the flavoring, and stir it until it looks clouded, and turn it at once over the cake.
CHOCOLATE ICING No. 1
Melt in a dry saucepan some chocolate; dilute it with a little water and add enough powdered or confectioner’s sugar to make it of the right consistency. Use it while warm, as chocolate quickly hardens. Flavor it with vanilla.