1Heat oven to 400ºF. Stir together sugar, butter and shortening in large bowl. Stir in vanilla and eggs. Stir in flour, baking soda and salt.
2Divide dough into 3 equal parts. Stir 8 drops yellow food color into 1 part dough to make yellow dough. Stir 8 drops yellow and 3 drops red food color into another part dough to make orange dough. Stir 10 drops red, 8 drops green and 3 drops yellow food color into remaining dough to make brown dough.
3Drop small portions of each of the 3 colors of dough close together in random pattern onto lightly floured cloth-covered surface. Roll doughs together into marbled pattern to 1/8-inch thickness. Cut with 2 1/2- to 3-inch leaf-shaped cookie cutter. Place about 2 inches apart on ungreased cookie sheet.
4Bake 6 to 7 minutes or until no indentation remains when touched in center. Remove from cookie sheet to wire rack. Cool completely, about 30 minutes.