Preheat your oven to 350 °F.
Line an 8x8-inch baking dish with baking paper.
In a microwave-safe bowl, place the chopped chocolate and microwave on high forabout 1 ½-2 minutes or until melted completely, stirring after every 20seconds.
Removefrom microwave and stir until smooth.
In a large bowl, add the sugar, cocoa powder, oil, eggs, egg yolk, vanillaextract, espresso powder and salt and with a wire whisk, beat until wellblended.
Add the melted chocolate and with a wire whisk, beat until well blended.
Add the flour and mix until just blended.
Place the brownie mixture into the prepared baking dish evenly and with the back of aspatula, smooth the top surface.
Bake for approximately 30 minutes.
Remove the baking dish of brownie from oven and place onto a wire rack to coolcompletely.