Mix flour and salt. Cut in cold butter until crumbly. Add ice water until dough forms. Shape into a disk, chill 30 minutes.
Roll out, place in pie dish, crimp edges, dock bottom, and pre-bake at 375°F for 10 minutes.
Sauté onion, celery, and bell pepper in oil and butter for 4–5 minutes. Add garlic and spices, cook until fragrant. Stir in shrimp; cook until pink. Add flour and stir.
Pour in milk and cream, stirring until thickened, 3–5 minutes. Add lemon zest and juice. Season with salt and pepper. Let cool slightly.
Whisk eggs with mayo or sour cream. Add cheeses, parsley, and green onions. Fold in shrimp mixture.
Pour filling into crust. Bake at 350°F for 35–45 minutes until golden and set. Rest 10–15 minutes before serving.