Preheat the oven at 350 F. Spray an 8-inch square pan, add a parchment paper to the bottom and set aside.
Heat one tablespoon of butter in a frying pan and roast the pecans for about 5 – 7 minutes at medium heat until they are fragrant. Set aside 12 pecan halves for decoration. Coarsely chop the rest of the pecans.
Chop the chocolate bar into small pieces and set aside.
Heat the 1 ¼ cup butter in a medium-sized saucepan and melt the butter and chocolate together at medium heat. Once melted, get it off the heat.
In a bowl, whisk together castor sugar and light brown sugar together. Add eggs, one at a time and vanilla extract and mix. Add the melted butter and chocolate to it and stir again.
Take another bowl and sift the all-purpose flour, cocoa powder, salt and espresso together.
Add the dry ingredients to the wet ingredients and stir. Add in the roasted pecans and stir one more time until combined.
Place in the middle rack and bake to 30 minutes.The mixture would be leaving the sides of the pan and the middle will be fudgy.
Let the brownies cool in the pan for one hour at least before cutting them in pieces.
Notes
No Leavening Agent: Do not use any leavening agent such as baking powder or baking soda in this recipe to get the fudgy-ier and dense texture of brownies.Hand Mixing: Do not use an electric or hand mixer for these brownies because it will add too much air in the batter turning the brownies into cake-like texture.