Tip 1: Baking is a science, so measure all of your ingredients carefully for best results. Sift your flour three times to aerate it and remove any lumps. This helps create a light sponge. Also make sure your eggs are at room temperature.
Tip 2: When you start beating the mixture, use electric beaters on high speed to create air pockets. Then, to keep it light and airy, reduce the speed to medium and beat for 5 minutes or until a ribbon trail forms when the beaters are lifted. Don't beat for too long, as this can cause the mixture to become thin and lose its volume and airiness. When adding dry ingredients, use a large metal spoon to gently fold the mixture until just combined. Don't use a wooden spoon - they're thick and heavy, and can cause the mixture to lose air.
Tip 3: Don't open the oven door while your sponge cake is baking, otherwise it can flop in the centre. When your sponge is cooked, it will come away from the sides of the pan, and spring back when touched lightly in the centre
Most foam cakes recipes have no little or no chemical leaveners such as baking powder or baking soda; instead they depend on a large amount of either whole or separated eggs that are whipped and filled with air bubbles to providing the leavening ingredient to make the cake rise during baking. Because foam cakes have a high proportion of eggs to flour they have a light and spongy texture not found in butter cakes.
The basic types of foam cakes are Angel Food Cake, Chiffon, Genoise, and Sponge cakes.
Genoise (whole egg method) is a classic European cake; the eggs are heated in a double-boiler with sugar then beaten until thick and lastly combined with flour.
Both Genoise and separated egg cakes may contain butter to provide a moister and more flavourful crumb.
Classic Genoise and Biscuit Sponge cakes start off drier but with a sturdy structure, making them able to drink and hold lots of moisture. The extra moisture is added by sprinkling a soaking syrup onto each layer after they have cooled. Soaking syrup is simply sugar and water boiled together, and then a liquor, juice, or extract is added in a flavor that complements the cake.
The main difference between foam cakes and butter cakes is baking powder/soda is not used for leavening (rise) in foam cakes. Both foam cake methods use beaten eggs to give the cake volume, not a chemical leavener as in butter cakes. When the eggs are beaten air cells form in the batter and these cells will expand in a hot oven giving the cake its volume and structure. To make sure the beaten eggs reach their full volume, it is important they are fresh, the correct size and at room temperature.
Egg yolks are beaten with most (a little is used when whipping the whites) of the granulated white sugar (superfine or castor produces a finer textured cake and a smoother meringue) until the mixture is thick and lemon coloured (takes about 5 minutes). Beating creates tiny air cells which expand when the batter is placed in a hot oven.
In a clean bowl, whip the egg whites with a little sugar to produce a meringue. Start on low speed to break the whites up. When a foam appears on the whites, add the cream of tartar (approximately 1/8 teaspoon for every two large egg whites). (When whipping the whites, cream of tartar (acid) is used to stabilize them and helps the whites reach full volume.) Gradually increase the speed to medium-high until almost stiff and then add the sugar in a steady stream until the whites are stiff, but not dry. (Should be thick and shiny.)
Angel Food cake, Meringues and Dacquoise contains no fat (butter or egg yolks) and are made with only egg whites along with plenty of sugar to provide an extra sweet cake that is moist and tender.
Chiffon Cakes are made with oil and separated eggs; the oil and egg yolk produce a tender crumb, and beaten egg whites along with a small amount of chemical leavener, produces the light and airy rise.
Separated Egg cakes are the typical sponge; the egg yolks and egg whites are beaten separately then gently combined and folded in with the flour.
Sponge cake is a cake based on flour (usually wheat flour), sugar, and eggs, sometimes leavened with baking powder which has a firm, yet well aerated structure. A sponge cake may be produced by either the batter method, or the foam method.
Separated Egg Method cakes are sponge, angel food, biscuit, roulade, chiffon, meringue, dacquoise
The separated egg method is the most common and some recipes use both the egg yolks and whites (sponge), while others only use the egg whites (angel food, meringue).