Cook Lasagna Noodles: Bring a large pot of salted water to a boil and cook lasagna noodles according to package directions until al dente, about 8-10 minutes. Once done, drain the noodles and lay them flat on a clean kitchen towel to prevent sticking.

Make the Filling: In a mixing bowl, combine the mashed butternut squash, ricotta cheese (reserve some for later), Parmesan, egg, sage, salt, and pepper. Blend until smooth.

Prepare the Béchamel: In a medium saucepan over medium heat, melt unsalted butter until bubbly. Gradually whisk in all-purpose flour, cooking for about 2 minutes until golden. Slowly pour in warm milk while stirring continuously. Cook until the sauce thickens, about 5-7 minutes.

Assemble Roll-Ups: Preheat your oven to 375°F (190°C). Spread a thin layer of filling over each lasagna noodle, sprinkle mozzarella on top, and roll tightly. Place each roll seam-side down in a greased baking dish.

Bake: Pour half of the béchamel sauce over the bottom of the baking dish, arrange the lasagna roll ups on top, drizzle remaining béchamel, and sprinkle the rest of the mozzarella over the roll ups. Bake for 30 minutes or until bubbly and golden.

Garnish and Serve: Remove from the oven and let it rest for 5-10 minutes. Garnish with grated Parmesan, black pepper, and crispy sage leaves, if desired.