Line a lightly oiled 23 x 13-cm (9 x 5-inch) loaf pan with plastic wrap, letting the wrap hang over the sides. Distribute the pretzel sticks, cranberries and pistachios evenly in the pan.
Melt the chocolate in a double boiler until hot to the touch. Pour the chocolate into the pan and mix gently with a knife tip so the chocolate fills the spaces between the other ingredients.
Refrigerate until the chocolate hardens, about 2 1/2 hours. Grasp the edges of the plastic wrap and lift the confection out of the pan. Peel off the wrap. Using a hot knife, cut into 2.5-cm (1-inch) squares.