1. Preheat your oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish.
2. In a large bowl, combine the shrimp, cooked rice, and cheddar cheese.
3. In a separate bowl, mix together the mayonnaise, sour cream, lemon juice, garlic powder, paprika, cayenne pepper, salt, and pepper. Pour this mixture over the shrimp and rice, stirring gently to combine.
4. Transfer the shrimp mixture into the prepared baking dish, spreading it evenly.
5. In a small bowl, combine the crushed Ritz crackers with the melted butter, then sprinkle evenly over the shrimp mixture.
6. Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and the shrimp are cooked through.
7. Let it cool for a few minutes before serving, allowing the flavors to meld together perfectly.

One tip from my kitchen to yours: Try using fresh shrimp when possible for the best flavor. And remember, the key to cooking shrimp is not to overcook them—they should be pink and opaque.