Preheat the oven to 400°F (200°C).
In a bowl, mix together the Parmesan cheese, spinach, olive oil, garlic powder, onion powder, thyme, cayenne pepper, salt, and pepper.
Cut a pocket into each salmon fillet, stuff each fillet with the spinach mixture.
In a small bowl, mix the paprika, garlic powder, onion powder, thyme, cayenne pepper, salt, and pepper. Rub this seasoning mixture onto both sides of the stuffed salmon fillets.
Heat a skillet over medium-high heat and sear the salmon fillets for 2-3 minutes on each side.
Transfer the skillet to the preheated oven and bake for 10-12 minutes or until the salmon is cooked through.
Serve the blackened salmon stuffed with spinach and Parmesan cheese hot.