Fudge frosting is a type of topping for baked goods that is similar to both buttercream frosting and traditional fudge in that it takes on a heavy, thick consistency as it sets and sometimes hardens to the consistency of fudge. The use of the term "fudge frosting" sometimes simply implies chocolate, which is one of the key ingredients; frostings that use flavorings such as orange liqueur or fruit generally are not referenced as fudge, even though fudge candy can take on flavors other than chocolate. The basic ingredients — milk, sugar and butter — are all fairly standard across most recipes, with the main difference being the type and amount of chocolate that is added to the final frosting. Unsweetened, melted chocolate can be used, as can cocoa powder, which achieves a similar result that ultimately is a little more malleable for a longer time. Once completed, fudge frosting needs to be applied before it hardens too much, because it can become very thick and difficult, if not impossible, to spread on a finished cake.
One of the challenges that faces some who make fudge frosting is achieving a smooth consistency without breaking the frosting. This can be difficult because the sugar tends to interact with the other ingredients and cause sugar crystals to form, which results in a grainy texture when eaten. Slow heating over a double boiler and accurate heating using a candy thermometer are two ways to avoid this problem, as is using powdered sugar. There are recipes, however, that are not concerned about the presence of crystals in the final product and require little or no heating at all.
A very simple recipe for fudge frosting involves mixing sugar, cocoa powder and vanilla in a bowl. Butter that has been melted either on a stovetop or in a microwave is poured over the mixture and stirred until fully incorporated. Milk or half and half is then added to the bowl and whisked until the desired consistency is achieved. This version of the frosting tends not to be as dense as some others.
A more complex way to prepare fudge frosting is to place sugar, milk and butter into a pan and heat them until the sugar has dissolved completely and the butter is melted. Lard can be substituted for butter, as can margarine, with both providing slightly different textures and tastes. Once the mixture has just started to boil, it is removed from the heat and small pieces of chocolate are added and stirred in until they melt and thicken the frosting. The chocolate also can be melted in a microwave or double boiler and poured slowly into the mixture to make a thicker frosting. This fudge frosting becomes harder as it cools and is intended to be used very soon after it is made.