Preheat oven to 350° F. 

Line two baking sheets with parchment paper.

Using an electric mixer, beat margarine and sugars together until light and fluffy. Add egg, orange zest, and extract; mix well. In a small bowl, combine flour, baking soda, and salt. Slowly add to the sugar mixture, and mix until just combined. Stir in white chocolate.

Remove half the dough. Color the other half of the dough with orange food coloring.

Return all the dough to the mixer, and mix for 5 seconds (not longer) to marbleize. Using a ¼-cup measuring cup, scoop out heaping measures of dough onto the prepared cookie sheets, 6 cookies per sheet. 

Bake 20 to 22 minutes. Allow to cool completely before removing from pan.