Preheat your oven to 375°F so it’s ready when you need it.
Melt butter in a large skillet over medium heat, then toss in shrimp and oysters.
Season the seafood with blackening and Cajun spices. Sauté about 2 minutes per side, just until they start looking opaque.
Add spinach, mushrooms, and crabmeat. Cook everything together for 2-3 minutes, letting the spinach wilt down.
Pour in the heavy cream and let it come to a simmer. Sprinkle in both cheeses.
Stir until the cheese melts into the cream and you get a thick sauce. Fold in the green onions at the end.
Spoon the seafood mixture into an oven-safe dish and bake for 10-12 minutes, until it’s bubbly and just browned on top.
Serve hot with slices of French bread for dipping.