Preheat the oven and prepare the pan

• Preheat the oven to 175 °C.
• Grease and line an 8x8-inch pan with parchment paper on all sides.
• Set aside.

Brown the butter

• Place the butter in a saucepan over medium-low heat.
• Once it foams, stir and scrape the bottom and sides of the pan every 10 seconds.
• After 6-8 minutes the milk solids sink and turn brown; when the butter smells nutty and toasted and is deep golden brown, immediately transfer it to a heatproof bowl to cool.

Make the chocolate base

• Add the cocoa powder, oil, vanilla and chopped chocolate to the cooled browned butter.
• Mix until the chocolate has melted and the cocoa powder is completely dissolved.

Whisk the eggs and sugars

• In a separate bowl, crack the eggs and add the light brown sugar.
• Whisk until the sugar is completely dissolved in the eggs; this is crucial for a crackly top.
• Add the powdered sugar and mix until completely combined.

Combine the batter

• Add the cooled browned butter mixture to the egg mixture.
• Toss in the flour and chocolate chips.
• Mix until well combined.

Bake the brownies

• Transfer the batter to the prepared baking dish.
• Bake until the tops are shiny and a toothpick comes out with some crumbs clinging to it.

Cool and cut

• Let the brownies cool in the pan before cutting.
• Use a very sharp knife, run hot water onto the knife to warm it up, and wipe it clean with a wet paper towel between cuts.