Preheat the oven to 375°F.
Heat oil in a small pan over medium heat, then add onion and tomatoes, sprinkle with salt, and cook for 4 minutes.
Add shrimp and garlic, cooking for another 4 minutes until the shrimp turn pink.
In a bowl, mix mayonnaise, lemon juice, paprika, and parmesan until well combined.
Stir in the cooked onion, tomato, and shrimp mixture before transferring everything to an oven-proof baking dish.
Bake for 15 minutes until the top is golden and bubbly.