Peel and slice the potatoes as thinly as possible, use a mandolin if you have one.
Put the potatoes in a large sauce pan and cover with the milk and cream, season with 1 teaspoon of salt and loads of black pepper. Seasoning really makes this dish so dont be tight on the salt.
Crush the garlic into the mix and gently heat, do not boil or the milk and cream will boil over.
After about 10 minute the potatoes should just be starting to get a little soft.
Transfer the mixture to an ovenproof dish and level out the potatoes so they cook evenly. You can add as much or as little of the liquid as you like but bear in mind the liquid will reduce so make sure you put some liquid in. I usually put all of the liquid in to start with.
Sprinkle the potatoes with the grated cheese to just cover the top.
Bake in an oven on gas mark6 (200) for 40 minutes or until golden and bubbling. Pop tinfoil over for the first 20 minutes.
If you find the potatoes are too liquid you can carefully remove with a spoon or drain some of the liquid off about 15 minutes before the end.