Preheat oven to 375°F (190°C).
In a large bowl, cream together the butter, white sugar, and brown sugar until smooth.
Beat in the egg, orange zest, orange juice, and vanilla extract.
In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add to the creamed mixture.
Stir in cranberries and walnuts if using.
Drop dough by rounded tablespoonfuls onto ungreased cookie sheets.
Bake for 10 to 12 minutes or until edges are lightly browned.
Cool on wire racks before serving.