My sister does a fabulous pasta bake which is free on a green day (if you count the cheese as a healthy extra).
I don't know the exact recipe - it seems to be different every time she does it. Adjust quantities according to how many people you are feeding.
You need a whole load of vegetables to roast in the oven - obviously it depends what you like, but she uses any or all of the following: sliced onions, baby carrots, aubergine, butternut squash, mushrooms, courgettes, sweet potatoes - you get the idea. Cut them up into bit-sized pieces. Maybe add some whole garlic cloves as well. Put in a large flattish tin, spray with Frylight and cook in a reasonably hot oven until everything is nicely brown around the edges.
Meanwhile cook enough pasta - my sister uses fusili, but anything you like will do. Let everything cool down a bit then mix the vegetables and pasta with lots of seasoning, one or two tubs of Quark, and if you have some syns to spare, some low-fat boursin cheese.
Put it all into an oven dish and sprinkle grated cheese on the top. Cook in the oven until brown and bubbling.
You can prepare it all in advance and chill it, then cook it when you are ready.