Preheat oven to 350 degrees F. Line two baking sheets with parchment paper.
In a medium bowl, mix together flour, baking soda, baking powder, and salt. Set aside.
2 cups all purpose flour, ¾ teaspoon baking soda, ¼ teaspoon baking powder, ½ teaspoon kosher salt
In the bowl of stand mixer fitted with the paddle attachment or in a large mixing bowl using a hand electric mixer, combine the butter, granulated sugar, and brown sugar. Beat until light and fluffy, about 3 minutes.
8 tablespoons unsalted butter, ¾ cup granulated sugar, ¾ cup light brown sugar
Beat in vanilla extract and egg until well incorporated.
2 teaspoons vanilla extract, 1 large egg
Mix the dry ingredients and wet ingredients together just until combined. Do not overmix.
Fold in macadamia nuts and white chocolate chips.
½ cup chopped dry-roasted macadamia nuts, 1 cup white chocolate chips
Scoop out 2 tablespoons of cookie dough and roll it into a ball. Place on a prepared baking sheet with 2 inches in between and repeat with the rest of the dough. Flatten each cookie to ½ inch thick (the bottom of a drinking glass or measuring cup works well for this). Bake for 8 to 10 minutes, or just until they start to turn brown on the outside.
Sprinkle the tops of the cookies with flaky sea salt when they come out of the oven.
Allow baked cookies to sit on the baking sheet for 2 minutes before moving to a wire cooling rack to cool completely.