Pat the salmon fillets completely dry with paper towels to remove all surface moisture.

Use a sharp knife to carefully create a horizontal pocket in each fillet by slicing into the side at the thickest part, cutting almost all the way through but leaving about half an inch intact on the opposite side and both ends to form a pocket.

In a small bowl, whisk together olive oil (or melted butter), lemon juice, garlic powder, paprika, salt, and black pepper. Rub this mixture generously inside each pocket and all over the exterior of the salmon. Let rest for 15 to 20 minutes at room temperature.

Chop the shrimp into small pieces. In a mixing bowl, gently fold together the lump crab meat, chopped shrimp, cream cheese, mayonnaise (or sour cream), grated Parmesan, minced garlic, green onions, celery, Old Bay seasoning, Cajun seasoning, lemon zest, and fresh dill or parsley. Use a light hand to avoid breaking up the crab lumps. The mixture should be creamy but hold its shape. Taste and adjust seasoning with salt and white pepper.

Preheat your oven to 400°F (205°C). Open each salmon pocket and spoon 2 to 3 tablespoons of the seafood stuffing into each fillet. Press the stuffing lightly into the pocket without overfilling. Brush the top of each stuffed fillet with 1 tablespoon of melted butter.

Optional step for deeper caramelization: Heat a skillet over medium-high heat with a little butter. Place the stuffed salmon skin-side down and sear for 1 to 2 minutes until lightly golden. This step can be skipped for easier weeknight preparation.

Place the stuffed salmon fillets on a rimmed baking sheet. Arrange one lemon slice on top of each fillet. Bake for 15 to 20 minutes, basting with 1 to 2 tablespoons more melted butter halfway through cooking to keep the salmon moist.

Check the internal temperature with a meat thermometer. You're looking for 125 to 130°F (52 to 54°C) in the thickest part of the salmon for perfect tenderness. The fish should be opaque on the outside but still slightly translucent in the very center.

Remove from oven and let the salmon rest for 5 minutes to allow the juices to redistribute throughout the fish. Garnish with fresh herbs and a squeeze of lemon juice. Finish with a drizzle of garlic butter over the top before serving.