Preheat your oven to 350?. Spray an 8x8 metal pan with nonstick spray and line with parchment paper.

Add cubed butter to a medium saucepan over medium heat. Melt the butter, stirring occasionally until it turns a deep golden shade with a nutty aroma.

Once the butter is browned, stir in semi-sweet chocolate until completely melted, then whisk in the vegetable oil and cocoa powder. Set aside to cool slightly.

In a large mixing bowl, add the eggs, egg yolk, and granulated sugar. Whisk for about 1-2 minutes until the sugar is fully dissolved.

Whisk in the powdered sugar, vanilla, and salt into the egg mixture.

Check that the chocolate mixture is no longer piping hot and whisk it into the bowl of eggs and sugar. Fold in the flour and espresso powder, then the chocolate chips.

Pour the batter into the prepared pan and bake for 29 to 32 minutes until the center has the slightest wobble and the top is shiny.

Let the brownies cool in the pan on a wire rack for about 1 hour and 20 minutes before slicing and enjoying.