7.

Spread 1/6th of the white sauce over the bottom of the baking dish and top with three lasagna noodles. Add 1/5 of squash puree and 1/4 of sautéed squash and apple mixture. Top with 1/6th of white sauce. Repeat with 3 more layers of noodles, squash puree, cooked squash mixture, and white sauce. At this stage, you should have used up all of the sautéed squash and still have 1/6th of the white sauce and 1/5th of the squash purée remaining. Place the final three noodles on top of the lasagna, top with the remaining purée, the remaining 4 ounces of shredded Gruyère, and drizzle with the remaining white sauce. Cover with aluminum foil, and transfer to the oven.