Using Heavy/Whipping Cream.Usually, it's a problem with lower fat dairy reacting with the acid in the coffee. That's why any of the milks below whole always split on me, and whole milk sometimes does. Anything half-and-half or higher stays together, but I keep it on the safe side and use heavy cream.
I think it also helps if you have your dairy at room temp or warmed a bit. It's the same issue I'll run into making cream of tomato soup - the acid in the tomatoes messes up the dairy if the fat content isn't high enough.
Yep, I know. I was just covering all the bases. Also, I know plenty of people who use "cream" as a generic term for any dairy (including me). Haven't you ever gone to a diner, ordered coffee, and have the waitperson ask, "Do you want cream for your coffee?" - and then set down those little packets of dairy that might be anything from skim milk to Coffee-mate? I have.But she didn't say she was using milk, she said cream.
Um...just about everywhere that serves breakfast, like Cracker Barrel, Bob Evans, Frisch's, McD's, BK, every diner...back when we were going to those places.And no, where are you going where they would do that?