Oven-baked rosti cake

Ingredients:
* 5 beef bacon
* 1.5kg potatoes
* 5 tbsp olive oil
* 1 small onion
* Butter, for greasing

Method:

1. Heat oven to 190C. Dry fry the bacon in a pan for 5 mins. until crisp, then chop into small pieces.
2. Boil the whole potatoes for 5mins, drain then place in a bowl of chilled water.
3. when cool enough to handle, pat the potatoes dry and roughly grate into a large bowl. Toss with the oil as you go, to stop them from sticking. Roughly grate the onion and squeeze out any excess juice, then stir into the potatoes along with the bacon. 
4. Place a baking sheet in the oven for 5 mins to warm through. Liberally grease a 2.3cm loose-bottom cake tin with butter. Scatter the potato over the tin, trying not to pack down, then dot all over the top with butter. Place on the hot baking sheet and bake in the oven for 1 hour and 20mins until the potatoes are cooked through and crisp on top.