In medium bowl, combine flour, baking soda and salt. In large bowl, beat butter, sugars and zest with electric mixer until light and fluffy. Add egg and, if desired, orange icing color; mix well. Add flour mixture to butter mixture; mix until just combined. Drop by tablespoonfuls or cookie scoop onto ungreased cookie pan.
Bake 12-15 minutes or until edges are golden brown. Cool 3 minutes on pan; remove and cool completely on cooling rack.
In microwave-safe bowl, melt white chocolate chips on 50% Power, stirring every 30 seconds, until completely melted. Drizzle melted chocolate over cookies.