1. Preheat the oven to 350 degrees.
2. Spray a 9x13 casserole baking dish with cooking spray.
3. Lay half the green chiles in the bottom of the dish.
4. Lay 2 or 3 shrimp on top of each chile. Cover with Cheddar cheese.
5. Create another layer of green chiles, shrimp, and Pepper Jack cheese.
6. Mix together the eggs, milk, flour, chili powder, and salt. Pour the mixture over the chile layers in the baking dish.
7. Bake for 50 minutes or until the top is browned and puffy.