Spaghetti doesn't really work for this recipe, but the other pastas are fine.
It is possible to add meat or fish to the recipe, but in my view it spoils the taste.
For Slimming World followers: This recipe originally had another stage to the method. After mixing together, pour into an oven dish and cover with grated cheese. Bake in a moderate oven until cheese is melted. This extra stage obviously uses cheese, so you would have to either use a Healthy Extra or syn the cheese. If you decide to do this, remember that whatever cheese you use can be divided by 6 to get the syn value for a portion.