In a large skillet over medium heat, melt the butter. Add the diced onion, celery, and carrots. Cook until the vegetables are tender, about 5 minutes.
Stir in the flour and cook for an additional 1-2 minutes to create a roux.
Make the Creamy Base:
Gradually whisk in the seafood stock or chicken broth, ensuring there are no lumps. Bring the mixture to a simmer and cook until it thickens, about 5 minutes.
Stir in the heavy cream, Cajun seasoning, garlic powder, onion powder, paprika, salt, and black pepper. Mix well.
Add the Seafood and Vegetables:
Add the shrimp, scallops, crab meat, frozen corn, and peas to the skillet. Cook until the seafood is just cooked through, about 5-7 minutes. Remove the skillet from heat.
Assemble the Pot Pie:
Preheat the oven to 375°F (190°C).
Pour the seafood mixture into a 9-inch pie dish or similar baking dish.
Place the pie crust over the top of the seafood mixture. Trim any excess crust and crimp the edges to seal. Cut a few small slits in the crust to allow steam to escape.
Bake the Pot Pie:
Place the pot pie in the preheated oven and bake until the crust is golden brown and the filling is bubbly, about 25-30 minutes.
Let the pot pie cool for a few minutes before serving.