Key lime cheesecake is cheesecake infused with key lime juice and sometimes the zest of the fruit as well. It is a popular variation on traditional key lime pie, which contains a green, gel-like key lime filling and egg white meringue on the top. Many types of key lime cheesecake only contain the flavoring, though a few varieties also feature a gelled layer and spikes of meringue. Cooks may make a key lime cheesecake very simply or infuse every part of it with traditional key lime flavors.
One of the simplest ways to turn an ordinary cheesecake into key lime cheesecake is to simply add key lime juice to the mixture. The cook should typically taste the mixture several times during preparation to make sure the citrus doesn’t overpower the other flavors. Some cooks also like to add a few spoonfuls of grated key lime zest to the recipe as well. Citrus zest is the thin, colored, outer layer of the skin on the fruit. It contains flavorful oils that usually brighten up a recipe.
Key limes are generally smaller, brighter, and greener than ordinary limes. The little keys are preferred as pastry ingredients because of their higher sugar content and bright smack of flavor. When gathering zest for a key lime cheesecake, the cook must typically gently rasp the lime against a fine-holed grater to get just the colored part of the skin. The white part underneath the zest, called the pith, is dry with a very unpleasant bitter flavor.
Zesting must usually be done before juicing because it is easier to zest a key lime when the fruit is firm. When juicing, the cook should typically roll the key lime between his or her palm and a hard surface, like a kitchen counter, to make the juices flow easier. The key lime may then be cut in half and squeezed to harvest the juice. A cook may need up to four of these tiny limes to get enough juice to flavor a key lime cheesecake.
Those making key lime cheesecake have two basic choices when it comes to color. The juice itself may give the cheesecake a slight green color, which may be plenty for some cooks. Other cooks may add a drop or two of food coloring to the mixture, to make it more green.
A third choice includes a variation on the cake itself. The cook may choose to pour a traditional key lime filling into the bottom of the crust, and then top it with a traditional cheesecake filling. From here, the cook may simply bake the cheesecake, or gently swirl the filling and cheesecake together to create a marbled effect before baking.