Preheat oven to 425 degrees. Peel pumpkin and cut into 1-inch chunks (about 4 cups). Toss with 2 tablespoons of the olive oil, 1/2 teaspoon salt, and the honey. Roast on a baking sheet until tender, about 45 minutes.
Meanwhile, bring a pot of well-salted water to a boil. Add pasta and cook according to package directions.
While pasta is cooking, heat remaining 2 tablespoons olive oil, garlic, and anchovies (optional) in a skillet over medium-high heat until fragrant, about 1 minute. Add walnuts and pumpkin. Toss to combine and heat through. Set aside.
Drain pasta, reserving 1 cup cooking water. Toss pasta with 1/2 cup cooking water and stir in parsley and Parmesan cheese. Season with salt and pepper, and drizzle with olive oil. Transfer to a bowl, and toss well with walnut and pumpkin mixture. Serve immediately.
Used butternut squash instead of pumpkin and it was just as tasty! Will make again...
Had this for dinner tonight and it was awesome! We swapped the parsley for fresh sage and the parmesan for gruyere because that was what we had on hand. This is a definite keeper!