Preheat oven to 350. Spread macadamias on a baking sheet or in a shallow pan. Bake, stirring once or twice, until lightly browned and fragrant, 5 to 7 minutes. Let cool. Leave oven set at 350. Line 2 large baking sheets with parchment paper or coat with vegetable oil spray.
In a medium bowl, whisk together flour, baking soda, and salt.
In a large bowl, combine butter, granulated sugar, brown sugar, and vanilla. Beat with an electric mixer on medium-high speed until light and fluffy, about 2 minutes. Beat in egg. Stir in flour mixture until well blended. Stir in macadamias and white chocolate.
Drop heaping tablespoons of dough 2 inches apart onto baking sheets (or use a 2-ounce ice cream scoop). Bake until cookies are golden brown at edges and no longer look wet on top, about 10 minutes. (Watch carefully during the last few minutes; these cookies can burn easily.) Let cool on baking sheets 2 minutes, then transfer to wire racks to cool completely. Store airtight at room temperature up to 1 week.