Preheat your oven to 400°F.
Season the salmon: Pat the salmon fillets dry with paper towels. Season both sides with paprika, garlic powder, salt, and pepper. Arrange the fillets on one side of a large baking dish and spray lightly with cooking oil.
Assemble the dish: Add the cherry tomatoes, sun-dried tomatoes, and minced garlic to the other side of the baking dish. Drizzle with olive oil, sprinkle with Italian seasoning, and toss gently to coat. Place the whole round of Boursin cheese in the center of the vegetables.
Bake uncovered for 15–17 minutes, depending on the thickness of the salmon, until the tomatoes begin to burst and the salmon is almost cooked through.
Broil (optional): For a lightly golden finish, broil for the last 1–2 minutes, watching closely to prevent burning. Make sure your baking dish is broiler-safe. The salmon should reach an internal temperature of 145°F in the thickest part.
Blanch the spinach: While the salmon bakes, place the baby spinach in a colander and slowly pour freshly boiled water from a kettle over it until wilted. Drain well.
Make the creamy sauce: Once the salmon is cooked, add the blanched spinach to the vegetable side of the baking dish. Break up the softened Boursin with a fork and stir it together with the roasted tomatoes, sun-dried tomatoes, and spinach until everything is coated in a creamy sauce.
Finish and serve: Drizzle with the lemon juice and adjust the seasoning if needed. Spoon the sauce and vegetables over the salmon, garnish with fresh basil or parsley, and serve warm.