Creamy Cajun Shrimp Pasta

Name: Creamy Cajun Shrimp Pasta
Ingredients: 1 pound raw large raw shrimp (26-30 count), peeled and deveined; 1 ½ teaspoons Cajun seasoning; 12 ounces fettuccine, preferably whole-wheat; 1 tablespoon extra-virgin olive oil, divided; 1 bunch scallions; 1 medium red bell pepper, thinly sliced lengthwise; 3 cloves garlic, minced; 1 tablespoon unsalted butter; ½ teaspoon ground pepper; 1 tablespoon all-purpose flour; 1 cup reduced-sodium vegetable broth; ½ cup half-and-half; 1 (5 ounce) package baby spinach; ⅓ cup sour cream; ½ teaspoon salt