Scalloped Sweet Potatoes & Butternut Squash

Preheat oven to 400ºF.

Peel sweet potato. Very thinly slice sweet potato and butternut squash. Set aside. Cut the ends off the leek. Cut in half lengthwise and slice the halves. Soak in cold water, separating the slices for 10 minutes.

Heat butter in a medium skillet over medium heat. When butter has melted, add leeks, cooking until they are soft, about 5–7 minutes. Sprinkle salt, pepper, sage, thyme, and flour over leeks. Cook for an additional 1–2 minutes until butter and flour have formed a roux. Stir in milk. Reduce heat to low. Simmer for about 7–10 minutes until sauce is slightly thick.

In a buttered 2-quart casserole, layer half of the sweet potato and butternut squash. Pour half of the sauce over the top. Layer the remaining sweet potato and butternut squash. Pour the remaining sauce over the top. Sprinkle Parmesan cheese evenly over the sauce.

Bake, covered, at 400ºF for 30 minutes. Uncover and bake 30 more minutes, until cheese and sauce are slightly browned and bubbly.