Pat salmon and shrimp very dry. Season salmon with salt, black pepper, and 1 tsp paprika, then drizzle with 1 tbsp olive oil.
Heat 2 tbsp olive oil in a large skillet over medium heat. Cook salmon 4–5 minutes per side until golden and flaky. Transfer to a plate.
Add butter and the remaining olive oil to the same skillet. Stir in garlic and cook 20–30 seconds until fragrant.
Add shrimp and season with salt, pepper, remaining paprika, onion powder, parsley, and cayenne if using. Cook 2–3 minutes until shrimp turn pink and tender.
Lower heat slightly and pour in heavy cream and lemon juice. Simmer 2–4 minutes until the sauce becomes glossy and lightly thick.
Stir in 1 cup mozzarella until melted and silky. Return salmon to the skillet so it warms gently in the sauce.
Sprinkle the remaining mozzarella on top. Cover 1–2 minutes until melted.
Spoon the creamy shrimp and salmon over warm rice and add plenty of sauce.
