Take chunky chopped potatoes and steam in oven or boil until al dente, then dry out in moderate oven for 10 mins

Make béchamel sauce, season to taste and rest. Add in extra milk with whisk.

In an oven proof dish place potatoes. Add 2/3 of cheese to the sauce and stir in well, add mustard to sauce.

Pour sauce over potatoes and cover with cheese.

Bake in an 175C oven for 25 mins or until golden on and bubbling around the sides.