Melt the butter in a medium saucepan, whisk in the flour. Slowly add milk or broth while whisking. Cook and whisk until mixture thickens. Remove from heat and set aside to cool.
When the sauce has cooled, mix in the chicken, parsley, and season to taste with salt and pepper. Cover and place in the fridge for 2-3 hours.
Cut crusts from the bread and tear slices into ½ inch pieces. Place bread in a shallow bowl, and place the beaten egg in another shallow bowl.
Shape the chicken mixture into 8 balls, about ¼ cup of mixture, or about 2½ inches in diameter.
Preheat you oven to 180° C (350° F), get out a baking sheet and line with parchment paper, or simply grease with butter or cooking spray.
Dip balls into the egg then coat with the torn bread. Place on the prepared baking sheet.
Bake for 20 minutes or until heated through and the bread crumbs are toasted.
While the balls are baking, prepare the Mushroom Sauce.
To serve, spoon mushroom sauce on a serving plate, place the baked chicken balls on top, serve and enjoy with sides of your choice. Enjoy.