Preheat your oven to 350°F (175°C). This ensures your cookies bake evenly.
In a large mixing bowl, cream together the softened butter, dark brown sugar, and granulated sugar using an electric mixer until the mixture is light and fluffy. This should take about 2-3 minutes.
Beat in the eggs one at a time, followed by the vanilla extract, mixing until well combined.
In a separate bowl, whisk together the all-purpose flour, cornstarch, baking soda, and salt. Gradually add this dry mixture to the wet ingredients, mixing until just combined. Be careful not to overmix.
Gently fold in the white chocolate chips and macadamia nuts with a spatula until evenly distributed throughout the cookie dough.
Using a cookie scoop, drop dough onto prepared baking sheets about 2 inches apart. Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden but the centers are still soft.
Allow the cookies to cool on the baking sheets for about 5 minutes before transferring them to a wire rack to cool completely. Enjoy your fresh batch of White Chocolate Macadamia Cookies with a glass of milk or your favorite beverage!
