Heat skillet with some butter, stir-fry chopped onion under
medium-low heat until tender. Remove and transfer into a bowl.
Stir in the parsley leaves, crab meat, bread crumbs and flour.
In a small bowl whisk together mayonnaise, egg, Dijon mustard,
Worcestershire sauce, paprika and Old Bay seasoning, salt and
pepper to taste. Stir the crab mixture until combined well.
Line a baking sheet with wax paper. Make crab cakes into 12
flattened rounds. Chill the crab cakes, covered with plastic wrap
for at least 1 hour.
In a heavy skillet, heat 2 tablespoons butter over moderate heat
and cook the crab cakes until golden brown, about 2 to 3 minutes
on each side. Serve crab cakes warm.