The closest thing I've found so far is Stonyfield Farms smoothie thingies (the other yogurt smoothies are fake-sweet-gross-crap, but SF is all natural), but it's not quite thick and rick enough. Their yogurt is very custardy, and this came in little bottles and was heavenly. I'd get that at the corner market and a chocolate croissant every morning for breakfast and eat it on the Underground.

Damn, I miss London.