With just three ingredientspowdered sugar, vegan margarine, and vanilla soy milkthis is a basic recipe for a quick and easy vanilla vegan frosting. You can use this mock buttercream frosting on a variety of vegan cakes. Just be sure to use a vegan margarine for a vegan version. While margarine is not dairy-based, there can be traces of animal products in it. Dairy-derived whey, casein, or lactose often added to give it a butter-like flavor. This can be a problem for people with dairy allergies or who are very strict vegans. Some brands that are truly vegan include earth balance, blue bonnet light margarine, smart balance light margarine. Some strict vegans also avoid most kinds of refined sugar since it may be refined using bone char. Commercially-prepared powdered sugar is made from refined sugar, so that can create a dilemma in these cases. If you purchase only certified vegan sugar, you can make your own powdered sugar by processing granulated sugar in your food processor until it is powdered. It really is that simple. Many kinds of commercial powdered sugar also add some cornstarch, which you can do as well.