Pasta with Sausage and Red Grapes

Name: Pasta with Sausage and Red Grapes
Ingredients: 6 ounces mild Italian sausage, cut into 1-inch chunks; 1 tablespoon extra-virgin olive oil; 1 small red onion, halved and thinly sliced; 2 cloves garlic, chopped; 1 tablespoon plus 1/4 teaspoon salt (preferably kosher), divided; 2 cups seedless red grapes; 1 cup low-sodium chicken broth; 1/4 teaspoon red pepper flakes (or more to taste); 10 ounces whole-wheat orecchiette (or other short-cut pasta, such as farfalle or penne); 2 tablespoon grated Parmesan; 1/4 cup chopped fresh parsley (or 1/2 cup chopped fresh basil)