Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

Slice salmon fillets lengthwise without cutting all the way through and lay them skin-side down.

Brush tops of salmon fillets with half the olive oil and season with salt and pepper.

Heat remaining olive oil in a skillet over medium heat; sauté spinach, Italian seasoning, paprika, and cayenne pepper for about 2 minutes.

Remove from heat and stir in roasted red peppers, feta cheese, and Parmesan until well combined.

Spoon the spinach-feta mixture into the salmon pockets, not overflowing.

Bake stuffed salmon for 12-17 minutes until opaque and flaky.

Let it rest for a few minutes before serving.