Tuna Mornay

You know those days when you have hardly anything in the pantry and don't really want to face grocery shopping or take away for dinner? This is one recipe that I call on frequently!
(Thanks Mum)

Ingredients
1 oz butter
1 1/2 ozs grated cheese
1 tblsp flour
1 cup milk
1 chopped onion
pinch of salt
1 medium size tin of tuna
4 potatoes (approx)


Method
Preheat the oven to 180°c.
Peel, finely slice and cook the potatoes until just tender, set aside for later.
Melt butter in a saucepan with the chopped onion.
Blend in the flour and salt.
Add the milk, stirring constantly until thick.
Add the tuna and most of the cheese. Leave enough to sprinkle over the top for baking.
Layer the potatoes in an oven proof dish.
Top with the tuna sauce and sprinkle the left over cheese on top.
Bake in the oven until golden brown.