Combine 30g/1oz oft the cheese, egg, egg yolk and a little salt and pepper in a small bowl, stirring with a whisk. Gradually add the reserved ¼ cup cooking liquid (this ensures the egg doesn't scramble when you add it to the pasta) to egg mixture, stirring constantly with a whisk. Set aside.
Spray a large nonstick frying pan over medium-high heat with some spray oil. Add the bacon and cook until golden. Remove bacon and set aside.
Add the onion and garlic (also mushrooms if you are adding those) to the pan, and sauté until golden.
This is where you will need the stock, if the mushrooms, onions and garlic start to stick, keep adding a little of the stock and continue this process until the stock is almost gone and the mushrooms and onion have a nice golden color.
Add the pasta and bacon back to the pan; reduce heat and mix thoroughly.
Add the egg mixture, remove from heat and toss in pan to evenly coat.
Divide equally among two plates, season with salt and black pepper and sprinkle with some fresh parsley and the remaining parmesan cheese.
This recipe is gluten free, Slimming World and Weight Watchers friendly