Sprinkle chops with salt and pepper. Melt 2.5 tablespoons of butter in a large heavy frying pan over medium-high heat and brown chops on both sides, turning frequently so they do not stick. Remove from pan, sprinkle with tarragon, cover and keep warm. Add another tablespoon of butter to the pan drippings and saute onions for 3 minutes or until soft and golden. Spread two third of the onions in the bottom of a shallow casserole, arrange chops, tarragon-side down on top. Sprinkle lightly with thyme and cover with onions. Pour wine into pan, bring to a boil, add chicken stock, return to the boil and cook until liquid is reduced to about two third of a cup. Pour mixture over chops.
Combine bread crumbs and cheese, spread over onions and chops. Melt remaining 2 tablespoons butter and drizzle it over the crumbs. Bake at 200ºC or 30 minutes.
Serves 4.