A rich brown roux and the signature Cajun culinary trinity (onion, bell pepper, and celery) provide authentic flavors for this hearty dish. It's best served hot from the oven. Call ahead and ask your fishmonger to peel and devein the shrimp for you.
Peel and devein shrimp, if desired. Combine shrimp and Creole seasoning in a medium bowl; set aside.
Cook bacon drippings, flour, and oil in a large skillet over medium heat, whisking constantly, 20 to 25 minutes or until roux is the dark brown color of pecan shells. Add 1/3 cup onion and next 3 ingredients; cook 5 minutes or until tender. Add thyme and next 3 ingredients; cook 1 minute, stirring constantly. Add shrimp and 4 green onions; cook over medium-high heat 3 minutes or until shrimp are almost done; transfer to a large bowl.
Add broth to skillet, scraping bottom of skillet to loosen browned bits. Add whipping cream. Bring to a boil over medium-high heat; reduce heat, and simmer 6 minutes. Add to shrimp. Stir in cooked pasta; toss well to combine. Pour into a lightly greased 13" x 9" baking dish. Sprinkle with Parmesan cheese.
Bake, uncovered, at 350° for 20 minutes or until thoroughly heated. Garnish, if desired.
Christmas With Southern Living 2006