1. Preheat the oven to 400°F. Drizzle a little oil into a large baking dish, add the onion, butternut squash, chopped sage and garlic, then roast in the oven for 15 to 20 minutes until soft.
2. To make the béchamel sauce, melt the butter in a medium saucepan, then add the flour until you have a paste and cook for 1 to 2 minutes. Slowly add the milk, constantly stirring until it forms a thick sauce and add the ¾ cup of Parmesan.
3. In a separate pan heat a little oil and add the spinach, nutmeg and salt and pepper. Cook for a couple of minutes until the spinach has wilted, squeezing out any excess water.
4. Bring a pan of salted water to a boil, drizzle a little oil into it and cook the lasagna noodles for 5 minutes, to soften them. Put a layer of pasta into a 9 x 13-inch earthenware baking dish, top with a layer of the butternut squash mixture, a layer of béchamel sauce, some spinach and a sprinkling of Parmesan. Repeat the layers, ending up with a final layer of pasta.
5. Spread the remaining béchamel sauce on top. Rip the mozzarella into pieces and scatter these over the top with any remaining grated Parmesan. Place in the preheated oven for 25 to 30 minutes until the mozzarella bubbles and browns. Garnish with the whole sage leaves flash-fried in a little butter.
Wine: Aromatic and full-bodied whites like Chenin Blanc or a white Rhône.
Tip: This can be kept in the fridge for two days if covered in plastic wrap or frozen for up to 3 months. Defrost fully before cooking.