Preheat the oven to 400°F (200°C) and prepare a baking sheet lined with parchment paper.

Carefully slice the salmon fillets lengthwise to create a pocket for the filling.

Drizzle approximately 1 tablespoon of olive oil over the salmon and season generously with salt and pepper.

In a skillet over medium heat, warm remaining olive oil and sauté the spinach with Italian seasoning, paprika, cayenne pepper, and a pinch of salt and pepper for about 2 minutes.

Remove the skillet from heat and stir in roasted red peppers, crumbled feta, and grated Parmesan, mixing until well combined.

Spoon the spinach and cheese mixture evenly into the pockets of each salmon fillet.

Place the baking sheet with the stuffed salmon in the preheated oven and bake for 12 to 17 minutes until cooked through.

Remove the salmon from the oven and allow it to rest for a minute before serving.