How about equal parts cottage cheese and plain yoghurt.
Or just thick unsweetened plain yoghurt if you like.
Not tried it, but would be interested to hear if it works.
I'm surprised a Tikka Masala recipe would use fromage frais-as it is classified as a type of cheese. Definitely try the low fat yogurt or crème fraiche.
Half fat creme fraiche or yoghurt. Tikka Masala in India would be made with cream so the nearest thing to that in consistancy should do it. I would say that yoghurt could be a bit sour but by the time you`ve put all the spices in, you won`t taste it anyway. I`ve never heard of fromage frais in curry though.
I'm making a low calorie chicken tikka masala tonight and I am using natural yoghurt, doubt Mr Jules will notice any difference, but I'm hoping my scales will!