Preheat oven to 375°F (190°C). Grease a baking dish.
Heat olive oil in a skillet. Cook shrimp until pink, about 2–3 minutes. Remove and set aside.
In the same skillet, sauté garlic and spinach until wilted.
In a large bowl, mix cream cheese, sour cream, mayonnaise, mozzarella, Parmesan, ½ cup cheddar, paprika, onion powder, salt, and pepper until creamy.
Fold in cooked shrimp, crab meat, and spinach mixture.
Transfer mixture to baking dish. Top with remaining cheddar cheese.
Bake uncovered for 20–25 minutes, until hot and bubbly with a golden top.
Serve warm with tortilla chips, baguette slices, or crackers.