In small saucepan over low-heat, combine 5 T of the butter with the flour. Make a roux by cooking, stirring constantly for about 20 minutes until the mixture is golden brown. DO NOT ALLOW IT TO BURN. Remove pan from heat and set aside.
In large saucepan, heat 2 sticks butter, and add onions, celery, bell pepper and chopped scallions. Sauce until tender, about 5 minutes. Add 1/4 cup of the parsley, chicken bouillon granules, paprika, cayenne, garlic powder, and black pepper. Saute, stirring, for 2 minutes.
Add 4 cups water to saucepan and bring to a boil. Add roux and stir until thickened, about 1 minute. Add crawfish and scallion tops. Heat. Garnish with remaining chopped parsley. Serve over rice.