Dust cutlets with seasoned flour, shaking off excess. Holding end of bones, dip each in beaten egg to thoroughly coat then press both sides into breadcrumbs, shaking off any excess. Chill until ready to cook.
Cook potatoes in a saucepan of boiling, salted water for 15 minutes, until tender. Drain, return to pan and toss on low heat until dry. Mash well, then stir through milk and 15g of butter. Season to taste.
Meanwhile, melt remaining butter in a large heavy-based frying pan on medium heat. When foam subsides, cook cutlets in one layer, without crowding pan, for 2-3 minutes each side, until golden. Drain on paper towel and serve with mashed potato and steamed beans.