Step 1 (Prep the Fish): Place salmon fillets flat on a cutting board. Using a sharp utility knife, slice a horizontal pocket into the thickest side of each fillet, being careful not to cut all the way through. Thoroughly pat the entire exterior of the fish dry with paper towels.

Step 2 (Sauté the Greens): Heat a tiny splash of olive oil in a pan over medium heat. Add the minced garlic and sauté for 30 seconds until fragrant, then add the fresh baby spinach. Cook for 2 to 3 minutes until completely wilted. Remove from heat, let cool slightly, and squeeze out any excess liquid.

Step 3 (Mix the Filling): In a medium mixing bowl, vigorously stir together the cooked garlic spinach, softened cream cheese, crumbled feta or mozzarella, and fresh lemon juice until a uniform, creamy paste forms.

Step 4 (Stuff the Salmon): Divide the spinach-cheese mixture into 4 equal portions. Carefully spoon the filling deep into each salmon pocket. Press the top flap down gently to close. Secure the open edges with clean wooden toothpicks if needed.

Step 5 (Apply the Seasoning): Mix the smoked paprika, garlic powder, onion powder, oregano, thyme, cayenne, salt, and black pepper together in a small bowl. Brush the outside of the stuffed salmon fillets with the 2 tablespoons of olive oil, then generously press the spice rub all over the fish.

Step 6 (Bake to Perfection): Place the seasoned fillets on a baking sheet lined with parchment paper. Bake in a preheated oven at 200°C (392°F) for 12 to 15 minutes. The salmon is done when it flakes easily with a fork and reaches an internal temperature of 63°C (145°F). Rest for 3 minutes before serving.