Cut the bread in half. Generously spread the slices with peanut butter and jelly to make 4 sandwiches. Heat a large skillet or griddle over medium-high heat and melt half the butter. Whisk together the egg and milk and dip both sides of each sandwich into the egg mixture letting the excess drip off. Cook the sandwiches for a few minutes on each side until they brown. Melt the remaining butter in the pan as needed. Drizzle with maple syrup and confectioners’ sugar before serving.