Is there any way to save heavy cream that's already been whipped? Dinner plans were canceled at the last minute.
Not that I've ever come across. Sorry ... would liked to have said yes
Freeze it! One way would be to freeze individual swirls/blobs and then use them to top either hot chocolate or desserts.
Another is to fold in soft fruit, crumbled meringue into the whipped cream and pour the lot into a clingfilm lined loaf tin and freeze. Like a frozen Eton Mess. This is loosely based on Nigella's Meringue gelato cake. Very good standby dessert, and it's ready for your next dinner party.
You could use it as cream in your coffee or on porridge.
It's possible to re-whip it. Once. Beyond that, it turns to butter quickly. Otherwise, I vote for the coffee solution.