Melt the butter in a heavy bottomed frying pan over medium-high heat. Slice the endives in half lengthwise and add them to the pan, keeping the heat relatively high so that the butter browns (but does not burn!) and the edges of the endive caramelize. After a few minutes, when you really think you are in danger of burning the butter and/or the endives, turn down the heat to low and pour in the chicken broth. Sprinkle the sugar and lemon juice over the endives and partially cover. Simmer for 20 minutes or until tender. Salt and pepper to taste.