Place 1/2 cup broth in a small saucepan over medium heat; simmer until reduced to 3 tablespoons (about 6 minutes). Remove from heat.
Combine water and remaining broth in a large Dutch oven. Bring to a boil over high heat; stir in pasta. Cook, uncovered, 10 minutes or until al dente. Drain well; place pasta in a large bowl. Keep warm.
Heat a Dutch oven over medium heat. Coat pan with cooking spray. Add onion; cook 4 minutes or until tender, stirring occasionally. Add garlic; cook 1 minute, stirring constantly. Remove casings from sausage. Add sausage to pan; cook 6 minutes or until browned, stirring to crumble. Stir in greens; cook 2 minutes or until greens wilt. Add reduced broth, half-and-half, and cheese. Cook 4 minutes or until cheese melts and mixture thickens, stirring frequently.
Add sausage mixture to pasta, and sprinkle with salt and freshly ground pepper. Toss well to combine. Serve immediately.