1. Step 1: Prep Your Ingredients – Take out your pie crusts and let them thaw at room temperature while you prepare the filling. Next, peel and dice your onion, carrots, and celery into small, uniform pieces. Mince the garlic cloves. Then, peel and dice the Yukon Gold potatoes into 1/2-inch cubes. Finally, cut your cod into 1-inch pieces. If using shrimp and scallops, ensure they are peeled, deveined, and ready.

2. Step 2: Start the Vegetable Base – Melt the unsalted butter in a large, deep oven-safe skillet or Dutch oven over medium heat. Add the chopped onion, carrots, and celery. Cook gently, stirring occasionally, for about 8-10 minutes until softened and translucent. Stir in the minced garlic and cook for another minute until fragrant.

3. Step 3: Create the Roux and Add Liquids – Sprinkle the all-purpose flour over the cooked vegetables and stir constantly for 1-2 minutes. If using, pour in the dry white wine, scraping up any browned bits, and let simmer for 1-2 minutes. Gradually whisk in the broth, then the whole milk, then the heavy cream, whisking continuously to prevent lumps.

4. Step 4: Simmer and Thicken the Filling – Add the diced potatoes to the skillet. Bring to a gentle simmer, reduce heat to low, and let cook for 10-15 minutes, stirring occasionally, until the sauce thickens and potatoes are tender. Season with salt and black pepper to taste.

5. Step 5: Incorporate Seafood and Herbs – Stir in the frozen green peas. Gently fold in the cod, shrimp, and scallops and cook for 3-5 minutes, until the seafood is just cooked through (shrimp pink, fish flakes). Remove from heat and stir in parsley, dill, and lemon juice.

6. Step 6: Assemble the Pot Pie – Preheat oven to 400°F (200°C). Pour the hot seafood filling into a 9-inch pie dish or similar casserole dish. Place one pie crust over the filling, trim and crimp edges, and cut several slits in the top. In a small bowl, whisk together the egg and 1 tablespoon of water. Brush the egg wash evenly over the top crust.

7. Step 7: Bake to Golden Perfection – Place the pot pie on a baking sheet. Bake for 30-40 minutes, until the crust is deeply golden brown and the filling is bubbling. If the crust browns too quickly, loosely cover edges with foil. Let rest for 10-15 minutes before serving.