Preheat oven to 350ºF.

Place a small sauté pan over low heat; melt 2 tablespoons butter. Add onion and celery and cook until beginning to soften, about 6 to 8 minutes; do not brown. Add green onions and garlic and cook until fragrant, about 1 minute. Stir in Creole seasoning and lemon juice; set aside. 

Place a large sauté pan over medium-low heat; add the remaining 3 tablespoons butter and melt. Whisk in flour and cook, stirring constantly, until a dark blonde roux is achieved. Add cooked vegetable mix to roux and stir; stir in crawfish tails and cook until heated through. Remove from heat and stir in shredded cheese.

Line a shallow 10-inch pie pan with prepared piecrust. Spoon crawfish mixture into piecrust. Place in oven and bake until heated through and bubbly, about 15 minutes. Serve hot.