Preheat oven to 350°. Rub pumpkin with olive oil, salt and pepper, and roast for 30 min, until soft. Cool for handling. Peel and cut into 1” cubes (3-4 c). Keep warm and set aside.
Sauté sausage in olive oil, drain, set aside, and keep warm.
In a large, heavy skillet, such as cast iron, cook onion in olive oil over low heat, until softened (about 8-10 min). Add garlic, cooking 1 min. Add rice, butter, salt, pepper and chili flakes (if using). Cook 1 min over med heat, stirring constantly. Add wine and cook until absorbed (approx. 30 sec). Add thyme and warm stock (approx. 1 c at a time), allowing liquid to absorb before adding more. Reduce heat to a slow simmer and stir frequently. Do not cover. Cook (approx. 30 min) until risotto is al dente (soft like perfectly cooked pasta).
Stir in pumpkin, sausage and cheese, reserving a little cheese for plating. Taste and adjust seasonings. Garnish with fresh basil and more Manchego. Serve with warm bread and salad.
Tip: Good risotto takes time and attention. If cooked too quickly, it will be crunchy and require more liquid. If cooked too slowly, it will become mushy and rice grains will break. Taste frequently when most of the liquid is absorbed to judge its texture.
Time savers: Prepare pumpkin and sausage ahead; refrigerate seperately until ready to use, then reheat slightly before adding at the end. Also consider shredding cheese and chopping onions and garlic ahead.