Pat the shrimp dry with a paper towel. Place shrimp in a food processor fitted with a metal blade and pulse until finely chopped (do not over-process to a paste). Transfer chopped shrimp to a medium bowl.

To the bowl with shrimp, add 3 tablespoons of panko, red onion, red bell pepper, celery, 2 tablespoons chopped parsley, mayonnaise, Dijon mustard, egg, lemon juice, Old Bay seasoning, garlic powder, and 0.5 teaspoon black pepper. Mix gently until just combined.

On a small plate, combine the remaining 1 cup panko with 0.25 teaspoon kosher salt and 0.25 teaspoon black pepper. Using a 0.33 cup measuring scoop, form the shrimp mixture into 1-inch thick patties. Gently place each patty onto the panko mixture on the plate, coating evenly on both sides. Carefully transfer the coated shrimp cakes to a clean plate. You should have about 8 patties.

Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Once the oil is hot, add 4 shrimp cakes, ensuring they are evenly spaced. Cook for 3 minutes per side, or until golden brown and cooked through. Transfer cooked cakes to a serving plate.

Add the remaining 1 tablespoon of olive oil to the skillet and repeat the cooking process with the remaining 4 shrimp cakes.

Serve the shrimp cakes immediately, garnished with extra fresh parsley and lemon wedges. Hot sauce is an optional accompaniment.