Heat oven to 325°F. Lightly grease cookie sheet. In large bowl, beat egg white until foamy; add salt. Gradually beat in brown sugar until thick and glossy. Fold in cereal until completely coated. Spread as thinly as possible over cookie sheet.
Bake about 8 minutes, turning over with spatula after 4 minutes, until set. Let cool 2 minutes before removing from cookie sheet. Remove with spatula. Cool; break into pieces. Store in airtight container.