In a large mixing bowl, combine the shrimp, crab meat, mayonnaise, sour cream, shredded cheddar cheese, lemon juice, Old Bay seasoning, garlic powder, onion powder, salt, and pepper.
Transfer the mixture to a baking dish and spread it out evenly.
Sprinkle the crushed Ritz crackers evenly over the top of the casserole.
Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and the casserole is bubbly.
Let it cool for a few minutes before serving.
Notes:
Feel free to add other seafood like scallops or lobster for a more luxurious dish.