Preheat the oven to 375°F (190°C).
In a large skillet, melt butter over medium heat.
Add flour to the melted butter, stirring constantly for 2-3 minutes.
Gradually whisk in the seafood stock and heavy cream.
Stir in Old Bay seasoning, mixed vegetables, and seafood.
Pour the filling into a greased baking dish.
In a separate bowl, combine biscuit mix and milk.
Fold in shredded cheddar cheese into the biscuit mixture.
Drop spoonfuls of biscuit mixture over the seafood filling.
Bake for 25-30 minutes until the biscuits are golden brown.
Let cool slightly before serving.