[ViolaMum]

Sour cream works well with cocoa - you'll find it in a lot of chocolate cake recipes. Also lemon and citrus cakes.

Sweetened, it's great in place of custard sauce (creme anglais) or even whipped cream.

I use plain greek yogurt as a sub when I don't have sour cream or buttermilk. You can go the other way - use sour cream in a recipe where you'd normally use an acidic dairy. It's less tangy than buttermilk, so the flavor profile will be a little different, but you may like it better. You can thin it out with water or milk if need be.

You can even use it for some of the cream cheese called for in recipes. It will break in sauces if not treated gently, though, so I'd add it at the end of cooking. I've had success subbing for some of the cream cheese in cheese coffee cakes.

If you use it to sub for regular milk in baking, you might want to add a little baking soda (1/4 t per cup of flour) to take advantage of the acidity and get more rise. Not necessary, but fun to experiment with.

Red velvet cake
Chocolate cake
Biscuits
Scones
Pancakes
Waffles
Coffee Cake (really good in a crumb cake!)
Madeleines

(Umm, yeah, I like to bake.)