There are two classic ways to get tub frosting to harden – lower the temperature or increase the amount of dry ingredients. Chilling the frosting helps firm it up temporarily, but adding a dry ingredient, such as sugar, helps harden the frosting up permanently. Either way, the resulting frosting will be harder than it was in its normal state at room temperature. However, tub frosting will never get rock hard, as it’s made to remain somewhat moist and creamy.
Hardening Tub Frosting
Chilling and adding sugar are the two tastiest ways to harden tub frosting. Simply place the tub in the refrigerator and chill for a few hours, depending on the size of the tub, to firm up the frosting. Add sugar to the frosting by first scooping the desired amount of frosting from the tub and placing it in a bowl. Beat powdered sugar into the bowl of frosting, adding a little at a time, until the desired consistency is reached. You can also add other dry ingredients, such as cornstarch, to the frosting. However, using dry ingredients other than sugar may alter the overall flavor.