Cook the noodles. Cook the lasagna noodles according to package directions until al dente. Drain and arrange them flat on a rimmed baking sheet or clean work surface. Lightly coat with cooking spray or a small amount of oil if overlapping to prevent sticking.

Prepare the squash filling. Combine 1 cup mashed butternut squash, ¾ cup ricotta, ½ cup Parmesan, the egg, chopped sage, 1 teaspoon kosher salt, and ¼ teaspoon black pepper in a large bowl. Mix until smooth. If the filling is too thick to spread easily, stir in some or all of the remaining ½ cup ricotta.

Start the béchamel. Melt the butter in a medium saucepan over medium heat. Whisk in the flour and cook for about 3 minutes, stirring frequently, until lightly golden.

Add the milk. Gradually whisk 2 cups of warm milk into the flour mixture until smooth. Add additional milk as desired for a thinner sauce. Increase the heat to medium-high and bring to a gentle simmer. Cook for about 3 minutes, whisking regularly.

Infuse the sauce. Reduce the heat to low. Add the whole sage leaves and smashed garlic cloves. Cook for 8–10 minutes, stirring occasionally, until the sauce is smooth and velvety.

Season the béchamel. Stir in ¼ cup Parmesan, nutmeg, cayenne, ½ teaspoon kosher salt, and black pepper to taste. Remove from the heat and set aside.

Assemble the Butternut Squash Lasagna Roll Ups. Preheat the oven to 375°F (190°C). Spread 2–3 tablespoons of squash filling evenly over each cooked noodle. Sprinkle each with 1–2 tablespoons mozzarella, then carefully roll the noodle from one short end to the other.

Prepare for baking. Remove and discard the whole sage leaves and garlic cloves from the béchamel. Spread half of the sauce over the bottom of a 9×13-inch baking dish. Arrange the filled roll ups in the dish and spoon the remaining sauce over them.

Bake. Sprinkle with the remaining mozzarella and bake for approximately 30 minutes, or until the cheese is melted and the sauce is bubbling with lightly golden edges.

Garnish and serve. Finish with additional grated Parmesan, freshly ground black pepper, and crispy sage leaves if desired. Serve warm.

Optional crispy sage. Heat about 1 inch of neutral oil in a small skillet over medium-high heat. Fry sage leaves in small batches for 20–30 seconds, turning once. Transfer to paper towels to drain and season lightly with kosher salt.