CUT EACH ENDIVE IN HALF lengthwise and set aside. Heat the butter and oil in a large skillet over medium heat on the stove. Add the endive in one layer and cook until the outer leaves are nicely browned, about 7 minutes. Turn endives and brown the other side, about 4 minutes. (Do this in two batches, if necessary.) Add the broth, sprinkle with salt and cook until the liquid is reduced, about 10 minutes. Transfer the endive and its juices to a serving platter. Serve immediately.