Preheat oven to 180 degrees celsius (360 degrees fahrenheit).
Mince the garlic if you're including it and mix into softened butter (place in microwave for 30 seconds form the fridge to soften). Put half in your baking dish and use this to grease the baking dish. Set aside the remaining butter.
Peel potatoes and onion and slice thinly.
Arrange about ⅓ of the potato slices on the bottom of the baking dish.
Arrange about ⅓ of the onion on top of the potatoes as the next layer.
Sprinkle about ⅓ of the cheese as the next layer.
Pour ⅓ of the cream over the layers and add a little salt and pepper.
Repeat these steps two more times, but adding the cheese and onion as the final top layer (that is, add cream before these ingredients for the last layer).
Put dobs of the remaining butter on top of the final layer.
Cover with a lid or foil and bake for 45 minutes.
Uncover and bake for another 30 minutes.
Video
Notes
How long will it keep?It will last about 5 days in the fridge, so it's perfect for making up in advance the day before you're planning to serve it.
Can I freeze Potato Bake?I'm told you can freeze it for up to a month. I wouldn't know from personal experience as ours always gets eaten before I can even think about freezing!
What is the best way to re-heat this dish?If frozen, allow it to thaw before re-heating. It can be re-heated in the microwave (on low-medium power) or covered in the oven at 160 degrees celsius for half an hour.
TIPS:
Be prepared! This dish needs at least one and a quarter hours of cooking time. You could cheat and par boil or microwave the potatoes first, but I don't recommend that if you want perfect potato bake.
Get the layers right, starting with potato at the bottom and finishing the top with cheese.
Cook covered to start with and then uncovered for best results.
Cook a day head if you want potato bake as pictured above. Here, I've allowed to cool and then cut a square of potato bake and re-heated in the microwave oven – to show off those lovely layers. This is perfect if you're having a dinner party and want to get a bit fancy, for example. However, it tastes just as good scooped straight out of the dish.