3 cups water

1 tablespoon butter

3/4 cup uncooked quick-cooking grits

2 ounces grated Parmesan cheese (about 1/2 cup)

5/8 teaspoon kosher salt, divided

3/4 teaspoon freshly ground black pepper, divided

2 center-cut bacon slices, chopped

1 cup chopped white onion

1 tablespoon minced garlic

1 (8-ounce) package presliced mushrooms

1 pound medium shrimp, peeled and deveined

1/2 teaspoon crushed red pepper

1/4 cup half-and-half

1 tablespoon all-purpose flour

3/4 cup fat-free, lower-sodium chicken broth

1/3 cup chopped green onions