Homemade marshmallow sauce is so ridiculously easy to make that you'll chuckle at yourself for ever having assumed it was complicated. Making it also allows you to use pure vanilla extract, which tastes so much better than the fake vanillin flavoring in many commercial versions.
Cooks' note:
•You can substitute in pasteurized egg whites with no trace of yolk, such as Eggology. Use amount to equal 1 egg white. Leftover sauce keeps, covered and refrigerated, for several weeks.