Mrsfrog, in answer to your question, NO, you only store this at room temperature. Never ever in the refrigerator.
my mom use to make this icing with a chocolate cake when i was a small girl.
I am 70 yrs old. How do you keep icing stored - in frig. covered? thanks,ladyfrog.
in response to "jumpygrouch's" comment. I believe I've figired it out! If you go back to the cake recipe this frosting is used w/you'll see this seven minute recipe has 1/4 cup store bought lemon curd, whisked into it. this is just my brain trying to make sense of less egg whites. But, if this is the case then this frosting recipe would be less confused if called "seven minute lemon tart frosting" or somthing more creativly Martha inspired.
This frosting is quite different from the 7-minute frosting listed for the White Cake with lemon curd filling, and I'm wondering if there's a typo in one or the other, as I can't believe they'd be that different since all you do is add coconut shavings to it after you've made the cake. For example, in this one, for 3 egg whites you have 1 1/2 cups sugar, and in the other it's 6 egg whites with the same amount of sugar...