Preheat oven to 360 degrees F (182 degrees C). Butter a baking sheet.
Gently mix cracker crumbs, 1/2 cup mayonnaise, egg, butter, parsley, seafood seasoning, mustard powder, black pepper, and Worcestershire sauce together in a bowl; fold in crabmeat. Form crabmeat mixture into patties, about 2 tablespoons per patty. Arrange patties on the prepared baking sheet.
Bake in the preheated oven until crab cakes are golden brown, about 30 minutes.
Blend 1/2 cup mayonnaise, roasted red peppers, and cayenne pepper together in a food processor or blender until smooth and creamy. Serve alongside crab cakes.