Heat oven to 200C/180C fan/gas 6. Tip the pumpkin into a large roasting dish. Toss in the oil, season and roast for 40 mins, stirring once.
Meanwhile, cook the gluten free pasta following pack instructions, reserving a few tbsp of cooking water. Place the spinach in a large colander and pour over boiling water to wilt. Allow to cool a little, then squeeze out as much excess water as possible. Pop into a bowl with the sage, lemon juice and zest, nutmeg and seasoning, then stir.
Next, tip sliced mozzarella into the hot drained pasta. Stir, adding a few tbsp of the cooking liquid. Mix most of the roasted veg and spinach mixture with the pasta. Divide into bowls and serve.