In a Dutch oven cook pasta according to package directions, adding kale during the last 30 seconds; drain. Return to pan, cover and keep warm.
While the pasta is cooking, start your sauce; in a large skillet melt the butter over medium heat, add the white wine and cook just a couple minutes until bubbling. Add the green onion, garlic and pesto. Continue to cook until the wine has reduced out a bit, about 2 minutes. Add salt, pepper, cayenne and fresh nutmeg.
Stir in the milk, canned pumpkin and one cup Parmesan cheese. After the cheese has melted, taste the sauce and add more seasoning or Parmesan if desired. The sauce should be nice and thick and will continue to thicken after it's mixed with the pasta. If you want to thin your sauce, add a little more milk and an extra tablespoon of butter. Taste again.
Add the sauce to about ¾ of the pasta, to coat. Add more of the pasta until your dish has the desired consistency.
Sprinkle individual servings with additional Parmessan cheese and, if desired, addditional green onions.