Two-Potato Gratin

from my sister-in-law's WW cookbook. It definitely helps to have a mandolin to slice up the potatoes.

2 large leeks, halved and thinly sliced (white and light green parts only)
2 garlic cloves, minced
2 tsp chopped fresh thyme
1/2 tsp salt
1/8 tsp black pepper
3 baking potatoes (1/2lb), peeled and thinly sliced
1 large sweet potato (3/4lb), peeled and thinly sliced
1/3c fat-free half and half
1/2 cup shredded Gruyere cheese

Preheat oven to 450, spray 2qt baking dish with nonstick spray

Spray large skillet with non stick spray. Over med heat, cook leeks until softened, about 8 min. Stir in garlic, thyme, salt and pepper.

Layer half of baking potatoes, covered by half the leek mixture, top with all sweet potatoes, then rest of leek mixture and remaining baking potatoes. Cover with foil and bake about 40 min or until tender when pierced with a knife.

Uncover and drizzle with half and half, sprinkle with cheese and. Bake uncovered until slightly brown about 12 min. Let stand 10 min before cutting into 8 servings.

Sprinkle with some coarse sea salt before serving.

Per serving: 143 cal, 3g total fat, 1 g sat fat, 0g trans fat, 7mg cholesterol, 194 mg sodium, 26g total carb, 4g total sugar, 3g fiber, 5g protein, 113 mg calcium.