In a mixing bowl, combine paprika, cayenne pepper, garlic powder, onion powder, thyme, oregano, salt, and black pepper to create the blackening spice mix.
Pat the salmon fillets dry with paper towels and coat both sides of the fillets evenly with the spice mixture.
Heat olive oil in a skillet over medium-high heat. Once the oil is hot, carefully add the seasoned salmon fillets to the skillet.
Cook the salmon for about 4-5 minutes on each side, or until the internal temperature reaches 145°F and the fish flakes easily with a fork. Remove the salmon from the skillet and set aside.
In the same skillet, reduce the heat to medium, and add the heavy cream, Dijon mustard, and lemon juice. Whisk together until smooth and heated through, about 2-3 minutes.
Taste the sauce and adjust seasoning if necessary. If you like a smoother sauce, you can blend it for a few seconds until creamy.
Serve the blackened salmon topped with the creamy Dijon sauce and garnish with fresh parsley if desired.