Ah, thanks everyone. I think it was Velvet Curtain's recipe I remember. I forgot it includes cream, I'll have to get a pot.
Failing lingonberry, I'm thinking cranberry sauce would work too?
Sainsburys have meatballs on half price just now and I'm wondering whether to stock up even more, but I've got limited freezer space, and some cooked chicken to freeze too....
BTW, the Sainsburys ones (they are a swedish brand, not own brand) suggest they can be served on pasta, as a sort of shish kebab or, assuming the little symbol of a hand means what I think, as a savoury snack. That would be lethal to me, I'd just eat the whole pack in one go!