Bring pot of water to boil, add 1 tsp salt and pasta. Cook as directed for al dente and drain in colander. Set pasta aside. In a saute pan heat 2 T olive oil, add garlic and shallots and saute until translucent and just about to brown. Add sausage, and break it into smaller pieces while sauteing until it loses its pink color. Add squash and stir until combined. Add water or broth and simmer until squash is tender and liquid has been reduced by approximately half around 10 minutes. Add pasta and 3/4 of parmesan cheese to pan and toss to incorporate pasta and sauce. Pour pasta into bowl and add arugula or spinach and toss to slightly wilt greens. Serve immediately.