Add the butter, bay leaves, fresh thyme and clove to a large pan.
Place the pan over medium heat until the butter has melted. Then fry the herbs and spices for 3 minutes until fragrant. In the meantime dice the meat up into large pieces. Don’t make them too small because they will shrink while stewing. Add the meat to the hot pan.
Stir and then brown the meat on all sides for 5 minutes. Add the chopped onion to the browned meat. Also add the strong mustard. Season generously with pepper and salt.
Stir the meat and onions well. Cook for 4 minutes. Then add the brown sugar. Pour in the dark ale and half of the warm beef stock.
Bring all the ingredients to a rolling boil. Then cover the pan and turn the heat low. Bring the stew to a simmer and cook it for 3 hours. Stir regularly. Add extra water, ale or beef stock if necessary. The meat should be very tender and the beer should almost have disappeared.
Turn the heat off and let the stew cool down for an hour. Then pour in the rest of the beef stock and add the pear molasses (optional).
Place the pan back over medium heat and simmer the stew uncovered for another hour until you end up with a nice sauce. Then check the seasoning and add extra pepper, salt, brown sugar or mustard to taste. Scoop the karbonaden stew onto deep plates and serve hot with fries.