I stick to making a low synned cheese sauce. Quark/Yoghurt etc toppings on a lasagne just make me go ewwww lol, I don't mind a spoonful on top of curry etc or as part of dessert, but that is where I draw the line.
All you need to make a cheese sauce is milk, cornflour and some cheese, far more tasty and you can fit the milk and cheese into a HEa portion when divided up.