Preheat oven to 425°. Spray a 9-inch deep-dish pie plate with cooking spray.
In a large bowl, stir together hash browns, green onion, melted butter, and 1 teaspoon Creole seasoning. Press mixture firmly into bottom and up sides of prepared pie plate.
Bake until golden brown, 30 to 35 minutes. Reduce oven temperature to 350°.
In a medium skillet, cook sausage, bell pepper, and celery over medium heat until sausage is browned and vegetables are tender. Spoon mixture into prepared crust. Sprinkle with cheese and crawfish.
In a medium bowl, whisk together eggs, half-and-half, and remaining ½ teaspoon Creole seasoning; pour over crawfish.
Bake until center is set, 35 to 45 minutes.
In a medium bowl, whisk together lemon juice, oil, mustard, and horseradish. Add arugula, parsley, tomatoes, and corn; toss to coat, and season to taste. Serve with quiche.
Recipe by Louisiana Cookin' at https://louisianacookin.com/crawfish-boil-quiche/