1. Preheat oven to 350 degrees, with racks in middle and lower third. In a food processor, pulse chickpeas until coarsely chopped. Add coriander, salt, pepper, flour, and butter, and pulse to combine. With machine running, gradually add 3 tablespoons cold water until dough forms a ball. Add Parmesan and pulse to combine.

2. Divide dough and form into two 1-inch-thick disks. On a lightly floured surface, roll out each disk to an 1/8-inch thickness. Brush with egg white and sprinkle with sesame seeds. With a knife, cut into 1-by-3-inch rectangles and place, 1/2 inch apart, on 2 parchment-lined baking sheets. Bake until golden brown and crisp, 25 to 30 minutes, rotating sheets halfway through. Let crackers cool on sheets.