If using the jam and graham crumbs, spread the jam onto the pie dough, leaving a 2-inch border. Sprinkle the graham crumbs over the jam.
Gently spoon the filling onto the dough, leaving a 2-inch border of dough.
Fold the dough over the filling, pleating as needed. Brush the edge with the whisked egg and sprinkle sugar over the dough.
Store the leftover galette in the refrigerator for up to three days.