Cake Stencils are one of the simplest ways to get a get a professional and highly impressive result when decorating a cake. They require very few tools, little know-how, and most importantly, they're quick and easy. In a pinch with a cake to decorate right this instant? You can even make your own in minutes!
But first, let's back up a bit. What is a cake stencil, exactly? Well, like a stencil, it is a device for applying a pattern or design to a surface by applying ink through perforations forming a design or words in a sheet of paper or plastic; the design that shines through when the stencil is removed is your finished design. You may remember them from school, as they are popular tools for teaching children number and letter forms; or maybe you have seen them used to make signs, or used to create graffiti! Basically a cake stencil has the same end result, but instead of ink and paper, your media will be entirely edible, and entirely sweet. You brush, sprinkle, or spray the coloring substance through the stencils perforations, and the design remains on the cake in the negative areas of the stencil.
Most commercially produced cake stencils will be made from some type of food grade plastic, which is easy to clean and ideal for multiple uses. They come in a variety of sizes, including ones that are flat and ideal for the top of cakes, or there are also long and skinny varieties (usually 4 by 12 inches or so) which are flexible, allowing for usage on the sides of either a square, rectangular, or round cake. There are even smaller stencils specifically designed for cupcakes!
You can also make your own stencils--it's really quite easy. Patterns are readily available online, and you can make it with a sheet of card stock and an X-acto knife (although, if you plan on re-using it, it's suggested that you use a food-grade plastic).
Fondant Topped Cakes: No doubt about it, fondant topped cakes are the easiest to stencil. Why? Well, their clean, flat surfaces are ideal for transferring a crisp, clean image. In recent years it has become quite common to use cake stencils to transfer delicate damask patterns or art deco motifs. Frequently, the image is transferred to the cake using royal icing as the "paint", applied with a piece of plastic or a pastry scraper. You can also use a stipple brush, although beware the icing seeping below the stencil if you use this method.
Buttercream cakes: It is possible to stencil a buttercream cake! Because buttercream is much more moist than a fondant topping, you do need to be a bit more careful about priming your "canvas". There are a few tricks. First, you've got to make the surface as flat as possible; try to ensure that you have leveled the frosting completely. Second, wait until the cake has set and is no longer soft or sticky--you don't want the icing to come off when you peel the stencil away, and you also don't want the image to bleed! Let the cake sit for a few hours before stenciling, or put the finished frosted cake in the fridge for about an hour (or as long as it takes to be solid to the touch). At that point, you can proceed with the stenciling, just as you did with the fondant covered cake.
Unfrosted cakes: A flourless chocolate cake in particular looks very pretty when topped with a design using a cake stencil, rendered in confectioners' sugar, which will add a beautiful contrast.
Other desserts: You can stencil non-cake desserts, too: Any dessert with a relatively flat surface can be decorated with a stencil. In Portugal, for instance, it is popular to use a stencil to top their rice pudding with a design made of cinnamon! I think that cheesecakes look quite pretty with a cocoa or cinnamon design stenciled on top.