In a large skillet, melt the butter over medium-high heat. Add the shallots and cook, stirring, for 30 seconds. Add the endive halves, cut side down and cook until golden brown, about 6 minutes. Turn and cook on the second side until golden, 3 to 4 minutes. Add the wine and season with salt and pepper. Lower the heat and cover and simmer until the liquid is nearly all absorbed and the endive is tender, about 10 minutes. Garnish with walnuts and parsley.