Preheat the oven - Set the oven rack in the middle of the oven and preheat to 350°F (180°C).
Prepare the baking pan - Brush melted butter all over an 8”x8” square baking pan. Line it with a piece of square parchment paper large enough to cover the bottom and the sides, fold excess parchment paper over the sides and use metal clips to secure if necessary.
Extra melted butter for pan
Brown the butter - Place the butter in a light colored saucepan over medium heat. Once the butter melts, it will become foamy. When the foam subsides, you will see clear bubbles, start whisking continuously at this point to keep the milk solids from burning. When the butter is caramel in color and smells nutty, remove from heat and set aside, but don’t let it cool completely.
4 oz unsalted butter
Mix dry ingredients together - Sift flour into a medium mixing bowl, stir in salt and ½ cup (86g) of dark chocolate chips along with the macadamia nuts. Set aside.
¾ cup all-purpose flour, ½ teaspoon kosher salt, ⅔ cup dark chocolate chips, 1 cup macadamia nuts
Bloom the cocoa - In a large heat proof mixing bowl, add boiling water to cocoa powder and stir to dissolve completely.
¼ cup cocoa powder, 5 tablespoon boiling water
Add chocolate chips - Immediately add the remaining chocolate chips (28 g) to the still warm cocoa powder mixture and stir to melt.
⅔ cup dark chocolate chips
Pour in brown butter - Slowly pour in warm brown butter, including all the brown milk solid, and stir to incorporate. Any chocolates that haven’t melted in the previous step should melt completely now.
4 oz unsalted butter
Add eggs and vanilla - Add the egg, and egg yolk along with the vanilla extract, and beat until smooth.
1 large egg, 1 large egg yolk, 1 teaspoon pure vanilla extract
Add sugar - Add sugar and beat again until completely incorporated.
1 cup + 2 tablespoon granulated sugar
Incorporate dry ingredients - Add the dry ingredient mixture prepared earlier into the wet ingredients. Fold gently with a spatula until combined and no trace of flour remains.
Bake - Transfer the brownie batter to the prepared baking pan. Bake in the preheated oven for approximately 30 - 35 minutes, until a toothpick inserted into the center of the brownie comes out almost clean with just a few crumbs attached.
Cool - Remove the brownie from the oven and let cool on a wire rack completely before cutting and serving.
Notes
Storage: store your brown butter brownies in an airtight container at room temperature for up to 5 days. You can also freeze them for up to 3 months.