I always make my cake with buttermilk and get rave reviews!! DO IT!

Oops! It is 1 tablespoon of vinegar or lemon juice to 1 cup milk. Sorry!

As the victim of overflowing cakes, I'd be careful about mayonnaise. I'd stick with ingredients that also have the same type of acidity as sour cream (like yogurt, buttermilk, or soured milk, which is 1 tsp vinegar to 1 cup milk).

How about mayonnaise? There are plenty of chocolate cake recipes with mayo as an ingredient.

I have omitted sour cream and used buttermilk, plain yogurt, or just regular milk in cakes with great results.

Creme fraiche if that's not a redundancy. Possibly buttermilk.

I just had to substitute sour cream in a recipe in order to make it kosher for a meat meal. I used tofutti's sour cream substitute and it worked out great.

1. Nigella's "Old Fashioned Chocolate Cake" has been marinating on my mind, like forever! Thanks so much.

2. @clotildenet (via twitter sent me)

me./

Plain whole Greek yogurt works.