Adapted from Cooking Light, Dec. 2012 - Delicious!
2
medium baking potatoes, peeled and cut into 1/4-inch-thick slices
2
medium sweet potatoes, peeled and cut into ¼-inch-thick slices
broth or water, for cooking potatoes
2
Tbs. canola oil
3
Tbs. all-purpose flour
2
cloves garlic, minced
1½
cups 2% milk
2
fresh thyme sprigs plus 1 ½ tsp. chopped fresh thyme
¾
tsp. kosher salt, divided use
¼
tsp. freshly ground black pepper
¾
cup shredded Gruyere cheese
¼
cup freshly shredded parmesan
Preheat
oven to 350 degrees. Place potatoes in a
large stockpot and cover with broth or water. Bring
mixture to a boil; cook for 4 minutes.
Remove from heat. Carefully
remove potatoes from pot using a slotted spoon, reserving cooking liquid. Arrange potato slices in a single layer on a
jelly-roll pan; set aside. Reserve 1 cup
cooking liquid.
Heat
a medium saucepan over medium heat. Add
oil to pan; sprinkle flour over oil; cook 1 minute, stirring constantly with a
whisk. Add garlic; cook 1 minute,
stirring often. Combine milk and
reserved 1 cup cooking liquid. Gradually
pour milk mixture into flour mixture in pan, whisking constantly. Add thyme sprigs to pan; bring mixture to a
boil; cook 3-4 minutes or until slightly thickened, stirring frequently. Remove from heat; strain. Stir ½ tsp. salt, pepper
and Gruyere cheese into sauce.
Spread
½ cup prepared sauce over bottom of a broiler-safe 2 quart ceramic baking dish coated with
cooking spray. Alternate baking potato
and sweet potato slices in shingle-like fashion across the bottom of the baking
dish. Sprinkle evenly with remaining ¼
tsp. salt and chopped thyme; pour remaining sauce over potato mixture. Sprinkle with parmesan cheese; bake at 325
degrees F. for 45-50 minutes, or until potatoes are fork-tender. Remove gratin from oven; preheat broiler to
high. Place gratin under broiler and
broil for 2-3 minutes or until nicely browned.
Now You're Cookin',
Chef Alli