To assemble tart, spread a thin layer of the shallot-Dijon mixture over the tart, leaving a 2-inch border on all sides. Sprinkle with all but 2 tablespoons of the cheese. Layer the zucchini so that it is just overlapping (you want lots of room for the steam to escape!) and finish with black pepper. Brush the dough border with egg wash, fold up and crimp the corners closed, and finish with more egg wash.