Cook Lasagna Noodles: Boil a large pot of salted water, add lasagna noodles, and cook until al dente (8-10 minutes). Drain and lay flat on a baking sheet to cool.

Make Filling: In a bowl, combine mashed butternut squash, ricotta, Parmesan, egg, sage, salt, and pepper. Mix until creamy and adjust consistency with remaining ricotta if necessary.

Prepare Béchamel Sauce: Melt butter in a saucepan over medium heat. Whisk in flour until golden. Gradually add warm milk while whisking continuously until thickened. Stir in sage, garlic, nutmeg, cayenne, salt, and pepper.

Assemble Roll-Ups: Spread butternut squash filling on each lasagna noodle, sprinkle with mozzarella, and roll tightly. Arrange in a baking dish, seam side down.

Bake: Preheat oven to 375°F (190°C). Spoon half of the béchamel sauce into the baking dish, place roll-ups on top, pour remaining béchamel over them, and add additional mozzarella. Bake for 30 minutes until golden and bubbly.

Garnish and Serve: Remove from oven, let cool for a few minutes, sprinkle with grated Parmesan and black pepper. Fry sage leaves in neutral oil for garnish if desired. Serve warm.