Preheat the oven to 240℃. Boil the macaroni according to the instructions on the packet, and drain. Mix the milk into the canned white sauce a little at a time.
The amount of milk added equals about half the white sauce can. Put the macaroni into a heatproof container, shred the chicken by hand and place it on top of the macaroni, then top with the white sauce.
Gently mix with a spatula or spoon so the sauce and the macaroni blend together evenly.
Sprinkle on some Parmesan cheese, and bake in the oven for 10-12 minutes until it browns. If you are using an aluminium tin, you can bake it in the oven.
Story Behind this Recipe
I was really busy at the end of the year, so I made a macaroni gratin, which is quick to make and my kids love. I heard that they make pie with chicken in the UK. The chicken pie I ate at the British Museum in London was really nice.
The canned white sauce is fully flavoured so you only need a little milk to thin it out. You can use rice instead of macaroni to make a doria (rice gratin), and if you don't have any chicken, canned tuna is fine.