Begin by boiling a large pot of salted water. Once boiling, cook the lasagna noodles for about 8–10 minutes until al dente. Drain and lay flat on a baking sheet.

In a mixing bowl, combine mashed butternut squash, ricotta cheese, grated Parmesan, egg, chopped sage, salt, and black pepper. Mix until smooth, adjusting with more ricotta if necessary.

In a saucepan over medium heat, melt butter. Whisk in flour and cook for 2 minutes until golden. Gradually add warm milk, whisking continuously until thickened for 5–7 minutes. Stir in sage, garlic, nutmeg, cayenne, salt, and pepper.

Preheat oven to 375°F (190°C). Spread butternut squash filling on each noodle, sprinkle with mozzarella, and roll tightly. Place seam side down in a greased baking dish.

Pour béchamel sauce over the roll-ups, cover with remaining mozzarella. Bake for 30 minutes until bubbly and edges are crisped.

Let cool for 5 minutes. Fry sage leaves in oil until crispy for garnish. Serve warm drizzled with béchamel and topped with crispy sage.