Preheat the oven to 400 degrees. Toss the butternut squash cubes with olive oil, minced garlic, sage, salt, and pepper. Spread them on a baking sheet and roast for 20 minutes until tender.

While the squash roasts, bring a large pot of salted water to a boil. Cook the lasagna noodles according to package directions until al dente. Drain and lay them flat on a lightly oiled surface.

Heat a skillet over medium heat. Add the spinach and cook for 2 minutes until just wilted. Remove from heat and chop roughly.

In a bowl, mash the roasted squash lightly with a fork. Stir in the ricotta, Parmesan, wilted spinach, and a pinch more salt and pepper.

Spread 1/2 cup marinara sauce in the bottom of a 9x13 baking dish. Spoon the filling evenly along each noodle, then roll them up and place seam side down in the dish.

Pour the remaining marinara over the rolls and sprinkle with mozzarella. Bake for 20 minutes until the cheese is melted and bubbly.