Sauté the vegetables: Melt butter and olive oil in a skillet, add onion and garlic, and sauté until fragrant. Add carrots, celery, and mushrooms; cook until tender.

Thicken the filling: Sprinkle flour over sautéed vegetables, stir, then whisk in broth and heavy cream until thickened.

Add seafood and season: Mix in paprika, Old Bay, shrimp, crab, peas, and parsley; remove from heat.

Prepare biscuit dough: Mix flour, baking powder, garlic powder, and salt. Stir in cheese, melted butter, and buttermilk until combined.

Assemble the pot pie: Pour filling into a baking dish, drop spoonfuls of biscuit dough on top, brush with butter, and sprinkle with parsley.

Bake and serve: Bake in the oven for 25-30 minutes until golden brown and filling is bubbling. Cool for 5 minutes before serving.