Frosting made with cream is rich and delicious, but it doesn't last long outside of your refrigerator. Whipped cream frosting is the most perishable, although other types of frosting also have a brief shelf life. Refrigerate cakes made with cream frosting and serve it within a few hours of removal from it.
Cream-based frostings typically include whipped cream frosting and ganache, although most frostings contain some type of dairy product. Cream is a perishable product, and frosting made with it should be refrigerated.
Storing Unused Frosting
To store leftover frosting that contains cream, pack it into air-tight plastic or glass containers and refrigerate it at 40 degrees Fahrenheit or less. Whipped cream frosting, which is generally nothing more than whipped cream, sugar and flavorings, quickly deflates and becomes watery. Refrigerate and use it within 24 hours. Ganache can be safely stored at room temperature for up to two days, says Cindy Mushet in "The Art and Soul of Baking." For longer storage, refrigerate it in a covered container for up to two weeks. Neither whipped cream frosting nor ganache freeze particularly well.
Storing Frosted Cakes
To store a cake frosted with a perishable cream-based frosting, chill the cake uncovered for 15 to 20 minutes to harden the frosting slightly. Then cover the cake loosely with plastic wrap and place it in the refrigerator. A cake decorated with whipped cream frosting becomes soggy quickly, so plan to eat it within a day or two. Add a bit of softened gelatin to the whipping cream to stabilize it and increase its shelf life. Ganache holds up better, but you should still eat the cake within three or four days. Bring the cake to room temperature before serving it.
Other Types of Frosting
Some dairy products are more perishable than others. Cream and cream cheese, for example, spoil more quickly than butter; you can safely store a cake decorated with buttercream frosting at room temperature for two or three days. Store leftover buttercream frosting in the refrigerator for up to one week, or put it in the freezer for up to six months. Cakes frosted with cream cheese frosting should be kept in the refrigerator, and leftover frosting used within one week.