Cook greens in boiling salted water just until wilted, about 1 minute. Drain; cool.
Melt 1 tablespoon butter in large saucepan over medium heat; add onion and garlic. Sauté until onion is translucent, about 5 minutes. Add sausage; sauté until brown, breaking up with spoon, about 3 minutes.
Add rice; stir 1 minute. Add wine; reduce heat to medium-low. Simmer until wine is almost absorbed. Add 1 cup broth. Stir until broth is almost absorbed. Add remaining 4 cups broth by 1/2 cupfuls, allowing broth to be absorbed before adding more.
Mix in greens after 10 minutes. Cook until rice is tender and mixture is creamy, 25 minutes total. Mix in cheese and remaining 3 tablespoons butter. Season with salt and pepper. Serve risotto, passing additional cheese.