To make these striped cookies, layers of chocolate shortbread dough and almond shortbread dough are stacked on top of each other.
Sift together flour, cornstarch and salt into medium-size bowl.
Beat together butter and sugar in medium-size bowl until blended. On low speed, gradually beat in flour mixture until soft dough forms. Divide dough in half; place each in a bowl.
Knead cocoa powder and vanilla into one half of the dough. Knead almond extract into other half. Flatten both doughs into a disk; wrap each separately in plastic wrap. Refrigerate 1 hour or until dough is firm.
Roll each batch of dough between 2 pieces of waxed paper into an even 10-inch square. If dough becomes too soft, refrigerate on a baking sheet.
Remove top piece of waxed paper from chocolate dough. Brush top with some egg white. Remove waxed paper from top of almond dough; invert onto chocolate dough. Peel off remaining piece of waxed paper. Cut dough into 4 equal strips. Brush strips lightly with egg white. Alternately stack strips. Wrap in plastic wrap. Refrigerate several hours or overnight.
To bake, heat oven to 375°F.
Cut dough crosswise into 1/8- to 1/4-inch thick slices. Place slices on ungreased baking sheets, spacing slices 1 inch apart.
Bake in 375°F oven 10 minutes or until edges begin to brown. Transfer cookies to wire racks to cool.