A carbonara sauce is pretty good - use lean
bacon (trim off all the fat), parmesan cheese is good because you don't need much as it is packed full of flavour. Or if parmesan is not on the menu at the moment, a diet cheddar cheese. Pretty much the same flavour as full fat cheddar, it works for us as we don't always have parmesan in the fridge. Don't need to use full fat cream either, replace it with the lower fat version.
Spaghetti bolognese is great. You can hide grated carrot, spinach, butternut squash, finely diced mushrooms, onions, tomatoes - all sorts of things. What they don't know will be good for them! I generally aim for 7 veg.
As to wholewheat pasta - I've not had any success (hate it myself), but it could well work for you. Even the tri-coloured spiral pasta could become a favourite as it is colourful, and has veg inside the pasta. I'm pretty sure (correct me if I'm wrong) that it uses wholewheat as well.
Or, take cooked/fresh lasagne sheets and turn them into ravioli. That way you can sneak lots of good things in there

And get a nice fresh sauce onto it, helps it go down more easily.
As Leeniek mentioned you do need to vary the diet, even though pasta seems to be a big favourite with your child. Try things like canned tuna and mashed potato patties. I don't know if soup is an option, but you can get so many veg into a pureed soup it ain't funny! And banana and yoghurt smoothies - they are terrific nutritionally. I often add canned peaches/apricots to them as well. great for the adult/s too. Although its probably not the season where you are for them, but they taste good anytime I reckon.
Ok, I've gotten slightly off track, I'll give someone else a turn.....