Instructions:
Place the squares on an ungreased baking sheet and brush them with milk very lightly. Sprinkle sea salt flakes onto each cracker. (Note: Sea salt flakes can be hard to find. Using granular sea salt is fine too, but be sparing.) Bake for 30 minutes until crisp but not browned. Transfer to a wire rack for cooling.
Note: Originally a British recipe, the measurements have been converted to American measurements for my own use.
For a variation, you can use black or white poppy seeds, or sesame, caraway, or celery seeds instead.