Prepare the seafood mixture: In a large skillet, melt the butter over medium heat until foamy. Add the diced onion, celery, and red bell pepper, sautéing for about 5–6 minutes until the vegetables are soft and aromatic. Stir occasionally to prevent browning too quickly. Once the vegetables are tender, sprinkle in the garlic powder and Old Bay seasoning, stirring to coat the mixture evenly with the spices. The aroma at this stage should be rich and slightly smoky.
Add shrimp and crab: Add the shrimp to the skillet and cook for about 2–3 minutes, just until they begin to turn pink and curl slightly. Be careful not to overcook them at this point since they will continue cooking later in the oven. Gently fold in the lump crab meat, being mindful not to break up the large pieces, so the pie retains texture and distinct bites of seafood.
Make the creamy sauce: Pour in the heavy cream, stirring slowly as it blends with the vegetable and seafood mixture. Allow the sauce to simmer gently for 4–5 minutes, or until slightly thickened. Stir in half of the shredded cheddar cheese and continue to mix until melted and smooth. The filling should be creamy but not runny — thick enough to coat the back of a spoon. Taste and adjust seasoning with salt and pepper as needed.
Prepare the biscuit topping: In a separate bowl, prepare the Cheddar Bay biscuit mix according to the package instructions. The batter should be soft and thick, ideal for spooning or spreading. This biscuit layer will bake into a golden crust over the creamy seafood filling, giving the pie its signature contrast of textures.
