Briazz Potato Stackzz

Pre-heat oven to 350°F (175°C).

Butter a 13 x 9-inch baking pan.

Slice potatoes 1/8 to 1/4-inch thick. Place in large pot, cover with cold water, bring to boil and simmer until barely tender, 7 to 10 minutes. Alternately, blanch by steaming until barely tender. Air-cool potatoes spread out on sheet pan, 10 to 15 minutes.

Meanwhile, cook leeks in butter until softened, about 7 minutes.

Prepare mustard sauce.

To assemble gratin, layer 1/4 of potatoes, 1/3 of sauce, 1/3 of leeks, 1/3 of cheese in pan. Repeat this process to create 3 layers. Cover tightly with foil.

Bake for 35 to 45 minutes or until potatoes are tender. Remove cover; bake 15 minutes until golden brown.