Preheat the oven to 160ºC /325ºF conventional oven. Prepare a 20x20 cm (8x8 inch) square pan with parchment paper.
In a medium sized saucepan add the butter and brown it over medium/high heat, takes about 8-10 minutes.
120 g butter
Pour the browned butter into a bowl, and make sure to scrape out all of the brown bits from the saucepan, as that’s all the nutty flavor. Add the cocoa powder and stir it in. The add the chocolate chips and stir them in until melted.
75 g semi-sweet dark chocolate chips, 35 g unsweetened Dutch cocoa powder
Sift together the flour, cornstarch, espresso powder and salt.
75 g all-purpose flour, 1 tablespoon cornstarch, 2 tablespoon instant espresso powder, ½ teaspoon salt
In a bowl, with an electric hand mixer, whisk together the eggs, brown sugar and granulated sugar until light and fluffy for 4 minutes. Add the melted butter and chocolate, oil and vanilla extract into the batter and mix until combined.
130 g granulated sugar, 130 g dark brown sugar, 3 large eggs, 70 g vegetable oil, 1 ½ teaspoon vanilla extract
Add flour mixture to the batter and on the lowest setting gently mix it together until combined. Scrape down the sides of the bowl with a spatula and add the extra chocolate chips. Gently fold them in until combined.
75 g semi-sweet dark chocolate chips
Pour the batter into the prepared baking pan and smooth it out. Bake for about 45-50 minutes. Serve once it’s cooled down. Finish it off with a sprinkle of sea salt.
A sprinkle of sea salt