Directions
In a large bowl, cream butter and sugar until light and fluffy. Beat in egg and extract. In another bowl, whisk flour, baking powder and salt; gradually beat into creamed mixture. Reserve 1 cup/250ml dough.

Tint remaining dough red; shape into a 3 1/2 inch/90ml long roll. Wrap in plastic wrap. Tint 1/3 cup/80ml of reserved dough green; wrap in plastic wrap. Wrap remaining plain dough. Refrigerate 2 hours or until firm.

On a lightly floured surface, roll plain dough into an 8 1/2×3 1/2-inch 22×9 cm rectangle. Unwrap red dough and place on a short end of the plain dough; roll up.

Roll green dough into a 10×3-1/2-inch/22.5×9 cm rectangle. Place red and plain roll on a short end of the green dough; roll up. Wrap in plastic wrap; refrigerate overnight.

Preheat oven to 350f/180C/Gas 4

 Unwrap and cut dough into  1/4 inch/6mm pieces. Place 2 inches/51mm apart on ungreased baking sheets. If desired, lightly press chocolate chips into red dough to resemble watermelon seeds.

Bake 9-11 minutes or until firm. Immediately cut cookies in half. Remove to wire racks to cool. Yield: about 3 dozen.