Ingredients
1 can (28 ounces) diced tomatoes in juice
1 tablespoon olive oil
3/4 pound sweet or hot Italian sausage, casings removed
1 small onion, finely chopped
Coarse salt and ground pepper
1 cup Arborio rice
1/2 cup dry white wine
1 bunch flat-leaf spinach (10 to 14 ounces), washed well, tough stems removed, chopped (about 7 cups)
1/2 cup grated Parmesan cheese, plus more for serving (optional)
2 tablespoons butter
