In a large mixing bowl, whisk together the egg, mayonnaise, Dijon mustard, Worcestershire sauce, and Old Bay seasoning until smooth.
Stir in the crushed saltine crackers and chopped parsley until evenly incorporated.
Gently fold the jumbo lump crab meat into the mixture using a spatula, taking care to keep the crab lumps intact.
Shape the mixture into 4 large patties, approximately 1 inch thick.
Cover and refrigerate the patties for at least 30 minutes to ensure they hold their shape during cooking.
In a large non-stick skillet, melt the butter over medium heat.
Place the crab cakes in the skillet and cook for 4 to 5 minutes per side, or until golden brown and the internal temperature reaches 165°F (74°C).