Preheat your oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, leaving some overhang for easy removal.
In a medium saucepan, melt the butter over medium heat. Continue cooking, stirring often, until it turns golden brown and develops a nutty aroma (about 5–7 minutes).
Melt the chocolate and butter in a double boiler, large heatproof bowl placed over a saucepan of simmering water or in a microwave in 30 second intervals.
To the melted chocolate whisk in the cocoa powder. Next, whisk in the vanilla extract.
In the bowl of a stand mixer or a large bowl with a hand mixer beat the eggs and both sugars at high speed for 6-8 mins until tripled in volume and the sugars are completely dissolved.Do not rush this step as this is what gives the brownies those shiny crinkly tops.
With the mixer on low speed beat the melted chocolate and butter mixture into the eggs.
Using a rubber spatula Gently fold in the flour until just combined. Avoid overmixing.
Fold in chocolate chips if using.
Pour the batter into the prepared pan and smooth the top. Bake for 25–30 minutes, or until the edges are set and a toothpick inserted into the center comes out with moist crumbs.
Allow the brownies to cool in the pan for at least 20 minutes before lifting them out using the parchment overhang.
Slice into squares and enjoy!