METHOD

Heat your pressure cooker over a medium heat then add the bacon and the onion - the fat released from the bacon will fry the onions. Fry for 4-5 mins till onions softened and translucent.
Pour the water or stock into your cooker along with the pasta, paprika, thyme, mustard powder and evaporated milk.
Close the lid, engage the lock and heat to high pressure. Once desired pressure is achieved turn the heat down to just maintain the correct pressure and start timing for four minutes.
When time is up, remove cooker from heat and let the pressure fall naturally (if you use the quick release method, you’ll have macaroni mash!). Pressure should stablise in one to two mintues. Remove the lid and don't worry if the contents look soupy or if some of your pasta looks undercooked.
Add your cheese (handfuls at a time) while stirring and then rest the mixture, lid on, for a further two mintues. Taste and adjust seasoning. 

Pressure cooker mac and cheese is best served immediately with some warm crusty bread (with lashings of butter - after all, there's none in the pasta!) and a green salad. Xavier sometimes likes to transfer the mix to an ovenproof dish sprinkled with extra cheese and some sliced tomato then grilled for a delicious grilled cheese topping. 

Supercharge it!
Add diced carrot or fresh peas, sweet corn or chopped broccoli. Left over roast beef, lamb, ham or chicken. Chopped sun dried tomato, any flavours, herbs, spices you like to the pressure cooker before cooking. Or add a splash of white wine while you’re frying the onions and change up the cheese with a lump of blue, cheddar, parmesan or a scoop of cream cheese for added decadence. And don't forget that American favourite, Lobster Mac and Cheese! Or drizzle with truffle oil!