Prepare rice according to package directions.
Melt butter in a large cast-iron skillet or Dutch oven over medium heat. Add onion and next 3 ingredients; cook, stirring constantly, 8 minutes.
Stir together soup and chicken broth. Add to vegetable mixture. Stir in Cajun seasoning and ground red pepper.
Cook over medium-low heat 10 minutes, stirring occasionally. Stir in crawfish, green onions, and parsley; cook 3 minutes or until hot. Serve over rice.
Note: To freeze, divide étouffée evenly into 3 (1-quart) zip-top plastic freezer bags. Freeze up to 1 month. Thaw in refrigerator overnight. Remove from freezer bag, and warm in a saucepan, stirring until thoroughly heated. Each bag contains about two servings.