Slice the leg pocket open to expose the inner leg meat to the surface of the pan. This will assist in even cooking. Chop the onion and parsley finely.
Dry off the chicken halves with paper towels. Heat up a 12 inch aluminium or cast-iron skillet over a medium-low flame. Pour in a small amount of peanut oil. Melt 1/2 Tbl butter in the pan. Sear the chicken, skin side down until well-browned, turn the halves over and season this side with salt and pepper. Sear the other side until well-browned, turn them over and season with salt and pepper. Check for doneness. (It takes about 8 minutes to fully cook halves of a de-boned chicken.) Remove the chicken from the pan and de-grease the pan.
Preheat the broiler. Place the oven rack on the rung closest to the broiler.
Melt 1 Tbl of butter into the pan. Throw in the onions, salt them down, and saute until they are clear. Add the parsley. Saute for a minute or so. Stir in the tomato paste. Cook for another minute. De-glaze the pan with wine. Make sure to scrape the bottom of the pan to lift off stuck-on residue. Add the Tabasco. Pour the juices which have accumulated under the chicken into the pan. Reduce the sauce slightly and adjust the seasoning with salt and pepper. Slide the chicken back into the pan. Turn the chicken in the pan to coat it with the sauce. Pile the Jarlsberg cheese on the skin sides of both chicken halves. Place the pan under the broiler unitl the cheese bubbles. Remove the halves to a serving platter. Check the sauce for consistency, then pour it over the chicken.