Before You Begin:
Prepare your cookware as needed. Cooking times and results may vary depending on your equipment and ingredients.
Prepare Oven and Fish
Preheat oven to 400°F (200°C) and line a baking sheet. Pat salmon dry and place on sheet.
Cut Pockets
Using a sharp knife, carefully cut a pocket lengthwise into each fillet without cutting all the way through.
Season
Brush salmon lightly with olive oil and season with salt and pepper.
Cook Filling
Heat remaining olive oil in a skillet over medium heat. Add spinach, Italian seasoning, paprika, and cayenne if using. Cook just until spinach wilts, then remove from heat.
Mix Filling
Stir feta, Parmesan, and roasted red peppers into spinach mixture until combined.
Stuff
Divide filling evenly among salmon fillets, pressing gently so it stays in place.
Bake
Bake for about 12–17 minutes, depending on thickness, until the salmon is opaque and flakes easily with a fork. The internal temperature should reach about 145°F (63°C) for safe doneness.