Boil the kettle - whilst you're waiting for it to boil chop the onion, mushrooms and gammon.
Cook the pasta as per instructions on the pack, and heat a large frying pan with a few sprays of low calorie cooking spray. Fry the onions until softened, add the mushrooms & gammon and cook till browned slightly.
Add the vegetable stock to the frying pan, and cook on high stirring frequently until it reduces by half.
Meanwhile in a bowl whisk the eggs, black pepper, quark and mustard (if you're using it!) - set aside.
Drain your pasta once it's cooked and tip into a big bowl, add the cooked onions, mushrooms, remaining stock and gammon - stir well. Slowly add the whisked eggs, Pecorino cheese and Quark making sure to stir constantly. Do NOT do this on the heat otherwise you'll end up with scrambled egg!