Angela, any old full fat plain yoghurt will do for cooking, as the taste is lost amongst the other ingredients, but it gives the same sort of richness as cream.
Prior to BSD, I always used supermarket’s own (generally Asda Greek). I only use Fage because it was recommended on here, so I tasted it and it is soooo delicious that I now have it for breakfast, with berries, every morning, so I always have it in the fridge. Plus it is a bit lower in carbs and calories than other plain Greek yoghurts. For example, 125g Fage (which is my breakfast serving) contains 6.25g fat (Asda’s 11.75), 4.75g carbs (Asda’s 8.25), 11.25g protein (Asda’s 6.38), and 120 calories (Asda’s 156) And, let’s be honest, on BSD800, every little carb / calorie saving helps 🙂
Mind you it is a lot more expensive so I guess I ought to really keep a carton of supermarket’s own for cooking with, and for the dogs for that matter, who get a portion each as a treat a couple of times a week, and also love to lick the cartons out as and when I finish them.