Step 1

Preheat oven to 350°F/180°C.

Step 2

Pour potato slices in casserole dish.

Step 3

In small bowl, combine powdered milk, flour, cornstarch, onion, chives, salt, mustard powder and black pepper. Stir well.

Step 4

Gradually whisk in water and mix to ensure no lumps remain.

Step 5

Pour over potato slices.

Step 6

Cut butter in small pieces and distribute over top of potatoes and liquid.

Step 7

Place in oven and cook for 40 to 45 minutes.

Step 8

Remove from oven and let rest and set for 5-10 minutes before serving.