A cake tester is a kitchen tool designed specifically for use in baking to test the doneness of cakes, a crucial step in the baking process. The design is very simple: a rounded ring or paddle handle holds a long, thin wire that is meant to be insterted into the cake as a probe. While testers are not vitally necessary for all cooks, they can certainly be useful.
After being inserted into a cake, if the tester comes out clean, the cake is done and it should be pulled out to cool. If crumbs or wet batter are left behind on the cake tester, the cake is not quite finished, and it should be allowed to bake a little longer. There are some exceptions to this rule; banana bread, for example, tastes best when there is still some residue on the probe.
All cakes should be tested for doneness before they are pulled out of the oven. Many things can affect the cooking time for a cake, starting with what kind of pan is used, how hot the oven actually is, and small variations in the ingredients. A recipe's published cooking time is often a close guide, but it is rarely perfect. For this reason, almost all recipes encourage cooks to test the doneness of cakes, specifying if residue should be left behind or not.
There are many substitutes for a cake tester that can often be found around the kitchen. Many cooks use toothpicks, which have the disadvantages of being non-reusable and sometimes too short. Other long, thin utensils like skewers, knives, and straightened out paper clips can be used as well. Some of these tools are also more likely to leave holes in the finished product, so caution is necessary when using them.
As a general rule, a cake tester should be made from metal, so that it is washable and reusable. Many are designed to be dishwasher safe, although in practice, their small size sometimes means that it slips out of the silverware rack and settles in the bottom of the dishwasher. Hand washing may be easier. It is also a good idea for cooks to look for a tester with a big, bright handle so that it can be easily found in a kitchen drawer.