Heat the oven to 350°F and line two baking sheets with parchment. Beat butter and both sugars until creamy, then beat in egg, vanilla and orange zest.
Whisk flour, baking soda and salt and mix into the butter mixture just until combined. Fold in cranberries and white chocolate chips.
Divide the dough into 24 rounded portions and place 2 inches apart, pressing very tall mounds down slightly.
Bake one sheet at a time for 10 to 11 minutes, until the edges are light gold and the tops have lost their wet shine.
Cool on the sheets for 5 minutes before transferring to racks. Let the white chocolate firm completely before packing.