Preheat air fryer to 400°. Cut sausages in half widthwise. Arrange in a greased 6-in. round baking pan. Place pan on tray in air-fryer basket. Cook until lightly browned, 6-8 minutes, turning once. , Meanwhile, in a large bowl, whisk eggs, milk, flour, onion powder, mustard, salt and pepper. If desired, stir in bacon; pour over sausages. Cook until puffed and golden brown, 10-15 minutes. Serve immediately and, if desired, garnish with parsley.