In a small bowl, combine flour (2 ½ cups), baking soda (3/4 teaspoon), and salt (1/2 teaspoon); set aside.
In a large bowl, cream butter (1 cup) and sugars (1/2 cup sugar + 1/2 cup) until light and creamy. Beat in egg (1) and vanilla (1 teaspoon) until smooth. Gradually add flour mixture until combined. Stir in orange zest (2 tablespoons) and white chocolate chips (12 ounces).
Drop rounded tablespoonfuls onto ungreased cookie sheets. Do not flatten cookies; it will make them dry. Bake for 8-11 minutes or until golden brown around the edges. Do not overcook! Cookies will be plump. Cool for several minutes on cookie sheets before transferring to rack to cool completely. Store in an airtight container.
Notes
Over-mixing– Over-mixing leads to gluten development, which makes for tough cookies. As you add the dry ingredients, stir until there is a streak or two of flour left. Then, finish mixing as you stir in the baking chips.
Zesting the orange- orange zest brings a big orange flavor. I like to use a Microplane to zest citrus fruit. Be sure to only take the orange rind and avoid the bitter white pith.
Butter- Be sure to use real, full-fat butter for the chewiest, most tender cookies. Margarine will not give you the same results!
White chocolate chips- I prefer actual white chocolate chips for the creamy, sweetness they bring. Vanilla baking chips, commonly mistaken for white chocolate chips, will work in a pinch, but you might lose a bit of the smooth, creamy taste.