Preheat the oven to 350. Line 2 cookie sheets with parchment paper.
In a small saucepan, melt 1 stick of butter over medium heat and cook, stirring often, until it is a very light golden brown. We just want a hint of brown butter flavor in this recipe. Remove from the heat. Add the remaining cold butter and stir until it is melted. Pour the butter into a large mixing bowl and allow to cool for 5 minutes. 1 cup (2 sticks) salted butter
After 5 minutes, add both sugars to the bowl and whisk until combined.
½ cup light brown sugar, ½ cup granulated sugar
Add the egg, egg yolk, vanilla, and lemon juice. Whisk vigorously for 1 minute.
1 egg + 1 yolk, 2 teaspoon vanilla, 1 teaspoon lemon juice
Add the salt, baking powder, baking soda, and cornstarch and mix until combined.
¼ teaspoon salt, ¾ teaspoon baking powder, ½ teaspoon baking soda, 2 teaspoon cornstarch
Add the flour and stir with a rubber spatula. When just a few white streaks remain, and the white chocolate chips and nuts. Mix until just combined, being careful not to overmix.
2 cups flour, 1 cup white chocolate chips, 1 cup macadamia nuts
Scoop the cookies into 50 gram scoops (**See notes). Bake for 12-14 minutes, until golden brown on the edges and the middle is still slightly underset.