Pumpkin Lasagna Rolls

Name: Pumpkin Lasagna Rolls
Ingredients: Kosher salt and freshly ground black pepper; 12 lasagna noodles; 4 tablespoons unsalted butter; 1 small yellow onion, chopped; 3 cloves garlic, sliced; 10 whole sage leaves and 2 tablespoons chopped sage, plus more leaves torn for serving (optional); 3 tablespoons all-purpose flour; 2 1/2 cups whole milk; 1/2 teaspoon pumpkin pie spice; 1 (15-ounce) can pure pumpkin; 1 cup grated Parmesan; 1 large egg; 2 cups whole-milk ricotta; 3 cups shredded mozzarella; Pinch crushed red pepper flakes; 1 tablespoon olive oil