Melt 3/4 cup butter in a large saucepan and sauté the onion and celery until tender. Add garlic and cook another minute, then stir in tomatoes, salt, pepper, crawfish, paprika, thyme, and bay leaves.

Blend the flour into the mixture, then whisk in the chicken stock. Add the scallions, cayenne, and Worcestershire; cook over medium heat for 15-20 minutes, stirring occasionally. When the sauce has thickened, remove bay leaves and fold in parsley. Add the remaining 2 tblsp. Butter to finish the sauce.

Serve over hot rice.