This delectable breakfast sandwich is a twist on the classic French "pain au chocolat" and makes a special breakfast ultra special. Pistachios complement the chocolate spread, adding texture, a satisfying crunch and wonderful color contrast. If you cannot find brioche at your grocery store, you can use a challah loaf or a plain white loaf - just make sure you buy an unsliced loaf so you can control how thick you want to cut the slices.