Combine flour, butter, salt and red pepper in medium bowl; beat at medium speed until dough forms. Add cheese; mix until a ball forms. Shape dough into circle; wrap in plastic food wrap. Refrigerate 2 hours or overnight.
Heat oven to 350°F Roll out dough on lightly floured surface to 1/4-inch thickness. (It will be hard to roll at first, but will soften. Press together any cracks that form on edges of dough.) Cut dough with 1 1/2-inch cookie cutters or pizza cutter into desired shapes. Place onto ungreased baking sheets.
Beat egg white and water together in small bowl. Brush cut-outs with egg wash; sprinkle with seeds.
Bake for 12 to 15 minutes or until very lightly browned around edges. Immediately loosen from pan; let cool on pan.
Shortbread can be topped with a variety of other ingredients such as chili powder, seasoned salt, fennel seed or herbs.