Usually those frostings in a tub are very sloppy and wouldn’t hold a peak unless you held it upside down. They also lack real flavor unless you get the fudge chocolate flavor. Then they don’t cover a whole sheet cake unless you spread it paper thin. It’s easy to make more!
Put the frosting in a bowl and add a cup of powder sugar. A stand mixer is the best for this kind of thing because you can let it fluff up your frosting while you do other things in the kitchen. Turn it on low to mix the powder sugar in. Don’t start on high – otherwise your whole kitchen will be powder sugar coated. Add the butter and mix in. Add another cup of powdered sugar until blended. Add a pinch of salt and a teaspoon of vanilla extract if you are making vanilla frosting.
If you are using chocolate frosting and want it to be very chocolaty – add 1/4 cup of choco powder. If you only add powder sugar to the pre-made chocolate frosting, it will get much lighter in color and will not really taste like chocolate. If the frosting is too thick after adding the choco powder, add a tablespoon or two of milk or cream – one tablespoon at a time – and check consistency. Vanilla extract is generally a waste in chocolate frosting because the choco over-powers the vanilla.
Depending on the volume of frosting that you need, either add another cup of powdered sugar and a tablespoon or two of milk or cream or turn the mixer on high. Now let the mixer do the work and fluff up the frosting for a couple of minutes – minimum. The test for consistency? Turn off the mixer and lift up the beaters or dip in a spatula. When you lift it and the frosting in the bowl holds the peak in it’s wake, it’s perfect! If it falls, add more powder sugar. If it’s rock solid and not fluffy, add a bit more milk/cream or butter and beat some more.