Step 1: Preheat Your Oven

Preheat your oven to 350°F (175°C). Line a cookie sheet with parchment paper and set it aside.

Step 2: Brown the Butter

In a saucepan, melt the salted and unsalted butter over medium heat. Continue cooking, stirring occasionally, until the butter turns a golden brown and gives off a nutty aroma. Be sure to watch closely to avoid burning. Once browned, remove the butter from the heat and let it cool.

Step 3: Combine Sugars and Butter

In a large mixing bowl, combine the dark brown sugar and granulated sugar. Add the cooled browned butter and beat the mixture until creamy. This step is crucial for ensuring the sugars are fully dissolved, leading to a smooth cookie dough. Next, add the eggs and vanilla extract, mixing until everything is fully incorporated.

Step 4: Prepare the Dry Ingredients

In a separate bowl, whisk together the flour, baking soda, baking powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Step 5: Add the Mix-ins

Gently fold in the white chocolate chip morsels, macadamia nuts, and pecans (if using). These mix-ins will create pockets of flavor and texture in every bite.

Step 6: Chill the Dough

Cover the cookie dough and chill it in the refrigerator for at least 30 minutes. For the best results, consider chilling the dough for 24 to 48 hours. This allows the flavors to develop and leads to a chewier, more flavorful cookie.

Step 7: Scoop and Bake

Preheat your oven to 325°F (163°C). Scoop the desired amount of dough onto the prepared cookie sheet, leaving enough space between each cookie for spreading. Bake for about 14 minutes, or until the edges are golden brown and the centers are still slightly soft.

Step 8: Cool the Cookies

Let the cookies cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely. This helps the cookies set and develop their final texture.