Preheat the oven to 375°F (190°C). Place the prepared pie crust in a 9-inch pie dish and set aside.

In a medium saucepan over medium heat, melt the butter until foaming. Add the mixed seafood and cook just until pieces turn slightly opaque — about 2–4 minutes depending on size. Avoid overcooking.

Pour in the heavy cream and sprinkle the Old Bay seasoning. Stir and simmer gently until the mixture thickens enough to coat the back of a spoon, about 3–5 minutes.

Reduce heat to low and add the shredded cheddar. Stir until the cheese melts and the filling is smooth.

Taste and adjust seasoning — a pinch of salt or a squeeze of lemon brightens it.

Pour the creamy seafood mixture into the prepared pie crust. Sprinkle the chopped parsley evenly over the top.

Bake for 25–30 minutes, or until the crust is golden brown and the filling is bubbling at the edges.

Remove from the oven and let the pie rest for 10–15 minutes before slicing.