Recipes will tell you what’s in a cake, but have you ever wondered how the ingredients work together?!
Temperature
Before you begin, make sure your oven is preheated to the correct temperature for the recipe, and let it come up to heat for at least 20 minutes.
While that’s happening, measure out your ingredients and bring them all up to warm room temperature too. This may mean warming ingredients, like milk and butter, in the microwave for about 30 seconds on a low setting to take the chill off.
Eggs, still in their shells, can be placed in a bowl of hand-warm water for 5 minutes as well, which has the added bonus of testing how fresh they are; Older eggs float because their porous shells have allowed air in over time, and the older they are, the higher they float. It doesn’t necessarily mean they’re bad, but you might want to crack them separately into another bowl to check they’re OK before use.
If all your ingredients are not of a similar temperature, your cake batter may look curdled/separated while mixing, and your baked cake could have a gummy layer along the bottom when you cut into it.
Mixing Method
Traditional Creaming Method - Start by whisking butter and sugar together, incorporating air, until pale and fluffy. Then whisk in eggs one at a time, mixing well between additions (with flavourings and optional sour cream), which adds more air and water. Then fold in flour last. The water in the eggs, plus agitation from stirring/folding, develops gluten in flour. Too much agitation however, could make too much gluten, and your cake becomes tough and rubbery. When mixed using this method, your cake should be lighter, airy, and slightly domed.
Reverse Creaming Method - Firstly, whisk (or rub) flour and butter together to fine crumbs. The butter coats the flour in fat, forming a barrier against water to restrict the formation of gluten. Next, stir in sugar and then beaten eggs. This adds water from the whites which the sugar hold onto. You need to work the mixture a bit at this stage to encourage some gluten (and therefore structure) to form, so lightly beat the mixture for about 2 minutes to encourage this. Reverse creaming should make a flatter cake that’s more tender and velvety with a finer crumb.
Butter
Butter contains approximately 80% fat and 20% water. Whisking butter together with sugar, whilst using the creaming method, joins the fat with more water (emulsifies), and also traps air, helping keep your cake moist and fluffy. When using the reverse creaming method, the fat coats the flour, decreasing gluten formation when eggs are added, so a softer, crumblier cake is promoted.
Sugar
Sugar is hygroscopic, meaning it attracts and holds onto water, making cakes moist. It is therefore classed as a wet ingredient in baking. It tenderises cakes, making them softer and somewhat crumblier too. If your cake turns out too dry and coarse, add a little more sugar next time. Adding too much sugar will over-tenderise the cake however, bringing on a collapse! Larger granules can struggle to dissolve in the batter and rise to form a crust on the finished product. Combat this by using caster sugar which has finer granules. Note: The darker the sugar, the more hygroscopic it is.
Eggs
Yolks - Add protein to cakes and build structure when mixed with gluten in flour. They also add richness and bind (glue) the cake structure into place. Yolks hold onto water in sugar too so if your bake is too dry or flat, add more yolks!
Whites - When whisked into the cake, they trap air and act as a leavening agent. If your cake turns out too gummy, add more whisked whites.
Flour
Plain - Without a raising agent. Made from milled soft grain like wheat, so therefore contains protein, starch and gluten (activated by water and agitation).
Self Raising - With added raising agent. Made from milled soft grain like wheat, so therefore contains protein, starch and gluten (activated by water and agitation).
Cake Flour - Without a raising agent. Contains less protein than other flours so less gluten is formed in resulting cakes. Makes a tender, more crumblier cake.
Cornflour - Without raising agent. Add to plain flour to imitate cake flour. 4:1 (4 parts plain flour to 1 part cornflour).
Starch - All flour contains starch, which forms gel bonds when activated by heat and water. So it thickens whatever it’s added to!
Salt
Adding a pinch of salt to a cake enhances flavour, but too much salt could make the cake firm and rubbery, as it reacts with the gluten in flour.
Raising Agents
Small amounts of raising agents create gas bubbles when water is added, so move quickly and get your cake in the oven ASAP to set those bubbles in position! Add too much and the extra bubbles will collapse, making the cake rough and bathroom sponge-like! Also, make sure the raising agent is mixed thoroughly into the flour before adding to the batter. If it isn’t, your finished cake could contain large uneven bubbles known as “tunnelling”.