Potato Au Gratin

Ingredients- 4-5 potatos, peeled and sliced
- 1 onions, peeled and sliced into rings
- 500ml milk
- 30g of flour
- dash of salt to taste
- 270g of cheddar cheese (white or red, up to you)
- 125g of butter (more, if you would like)

Method
1. Heat oven to 200c
2. Arrange the sliced potatoes (half) on the bottom of an aluminium tray
3. Top with onion rings
4. Cover with the rest of the sliced potatoes
5. Melt butter in a saucepan
6. Add flour and dash of salt and stir until the mixture thickens
7. Add milk and stir continuously
8. Add all of the cheese at one time and stir until the lumps dissolved
9. Pour mixture over the potatoes
10. Place in oven to bake for 1.5 hours.

Serve.