Combine the dry ingredients in a medium sized bowl: flour, baking powder, cornstarch, and salt. Whisk and set aside.
2 cups all purpose flour, spooned and leveled, 1 tsp. baking powder, 1 tsp. cornstarch, 3/4 tsp. kosher salt
In a small saucepan over medium-low heat, melt 1 cup white chocolate chips and butter. Whisk just until ingredients are melted and be careful to watch so chocolate doesn't burn. Careful not to turn the heat too high because the butter and white chocolate can separate. Remove from heat, whisk in vanilla and set aside to cool.
1/2 cup unsalted butter, 2 cups white chocolate chips, divided, 2 tsp. pure vanilla extract
Using a stand-mixer fitted with the whisk attachment, whisk the eggs and sugars for 3-4 minutes or until thick and pale in color.
2 large eggs, room temperature, 3/4 cup light brown sugar, packed, 1/4 cup granulated sugar
Using a rubber spatula, stir in the cooled chocolate/butter mixture until well combined. (White chocolate/butter mixture doesn’t have to be completely cooled, just so it’s not super hot).
Add in the flour mixture and fold just until combined.
Stir in remaining 1 cup white chocolate chips and chopped nuts. Try to avoid over-mixing. (Pro tip: pulse macadamia nuts in the food processor to chop them!)
1 cup macadamia nuts, chopped
Chill cookie dough in fridge for at least 10 minutes so batter can thicken and look more like cookie dough. (Chilling the dough will also help the cookies bake up thicker & help prevent spreading). Preheat oven to 350°F while dough chills.
Scoop batter using a 2 tbsp. cookie scoop so cookies come out even in size and place on a baking sheet or cookie sheet lined with parchment paper or a silicone baking mat. Bake for 10-12 minutes. The cookies will look puffy right when you pull them out of the oven.
Swirl a cup around cookies if needed to make perfect circles. Garnish with more white chocolate chips on top while they are still warm. Allow to cool on cookie sheet for 5 minutes, then transfer to wire rack to cool completely. Finish with flaky sea salt and enjoy!
flaky sea salt, for finishing