Preheat your oven to 425°F (220°C).
In a large pot, melt 2 tablespoons of butter over medium heat and add the diced onion.
Add the minced garlic and chopped spinach to the onions and cook until the spinach is wilted.
Stir in the flour, Old Bay seasoning, lemon juice, shrimp, and scallops, cooking until the shrimp turns pink.
Pour in the chicken broth and heavy cream, stirring to combine.
Let the mixture simmer for about 5-7 minutes until thickened.
Transfer the seafood mix into a baking dish, spreading it out evenly.
Prepare the Cheddar Bay Biscuit mix according to package instructions, then drop spoonfuls of the dough over the seafood filling.
Bake in your preheated oven for 20-25 minutes, or until the biscuits are golden brown.
Once done, allow the pot pie to cool for a few minutes before serving.