Combine milk and egg in a bowl. Dip each crab in milk mixture; dredge in flour.
Melt butter in a large skillet over low heat; add coated crabs, and cook until crabs are golden brown, turning once. Remove from heat; place crabs over toast points on a serving platter, and drizzle with Béarnaise Sauce. Sprinkle with parsley, if desired. Serve immediately.