Wash the chard. Cut off the white stalks and trim their ends and any discolored portions. Heat the oil in a covered pan and add the garlic and anchovies, allow this to cook until the anchovies have melted into the oil, about 5 minutes. Cut the chard stalks into 1-inch pieces, blanch them in boiling water and refresh under a cold tap. Drain well, add them to the oil and season with the pepper. Cover and cook gently for 10 minutes. If you wish you may add the chard greens at this stage and cook for a further 3 to 5 minutes or you may wish to use the greens for something else.