Crab Stuffed Salmon

Name: Crab Stuffed Salmon
Ingredients: 1/2 bunch fresh parsley; 10 Ritz or butter crackers (about 1 ounce); 4 (about 6-ounce, at least 1-inch thick) skinless salmon fillets; 4 teaspoons Old Bay seasoning, divided; 1 tablespoon olive oil; 1/2 medium lemon; 2 tablespoons mayonnaise; 1 tablespoon whole grain mustard; 1/2 teaspoon freshly ground black pepper; 8 ounces jumbo lump crab meat; 8 tablespoons (1 stick) unsalted butter; 3 large egg yolks; 2 teaspoons Dijon mustard; 1/2 teaspoon whole grain mustard (optional); 1/4 teaspoon kosher salt; 1/8 teaspoon cayenne pepper (optional)