Lightly oil the baking dish. Preheat oven to 375.
Slice the potatoes as thinly as possible and divide in half. Arrange half of the potatoes slice by slice in the baking dish.
Sprinkle with half the onions, yeast, and a dash of salt and pepper.
Repeat with remaining ingredients.
Pour milk over the top and jiggle the dish to allow the milk to settle. If there’s not enough milk to cover the top layer of potatoes, add a bit more.*
Drizzle with olive oil and sprinkle with paprika.
Bake for 45-60 minutes, until the top is golden and you can easily pierce the potatoes with a fork.