From Anthony Telfords the Basics directly - I've only ever made the full fat version pre-SW
Hash brown potato
Serves 4
500 g (about 2 large) potatoes
2 tablespoons vegetable or canola oil
2 tablespoons butter
salt and pepper, to taste
Method:
1. scrub the potatoes—they do not need to be
peeled—then coarsely grate. squeeze the grated potato
slightly to remove some of its water (this makes for a
crispier end result).
2. heat a 30-cm frying pan, preferably nonstick, over
medium–high heat. add the oil and butter.
3. When hot, add the potatoes and push down with a
spatula to spread evenly in the bottom of the pan.
sprinkle the top with salt and pepper. cook until the
bottom is browned and crispy, about 10 minutes. Do not
try to flip until it is browned, or the potatoes might
stick.
4. flip the hash brown, cut into sections if
necessary, and cook another 10 minutes, or until
browned and crispy on the other side.
5. serve immediately, or cool and simply reheat in the
microwave or preferably in a hot oven (210°c) for
5 minutes.
I think if your pan is good enough you can probably get away with oil OR butter, but I think you'll need at least one kind for it to work.
I squeeze the potato "juice" out by grating the potato into a clean teatowel and then wringing
there are loads of recipes if you google baked rosti or baked latkes - some with fancy additions like onions and eggs...