Preheat oven to 355 degrees F (180 degrees C).
Melt the Unsalted Butter (225 gram), Bittersweet Chocolate (170 gram), and Unsweetened Chocolate (55 gram) over a water bath, stirring until the chocolate is smooth.
In a large bowl, whisk together the Caster Sugar (370 gram) and Instant Espresso Powder (2 tablespoon), then add the melted chocolate and butter to the bowl.
Mix in the Large Egg (4) and Pure Vanilla Extract (1 teaspoon) until thoroughly combined.
Sift in the All-Purpose Flour (165 gram), Baking Powder (1 teaspoon), and Salt (1/2 teaspoon) and mix well.
Add Espresso (40 gram), reserving some to dust over cooked brownies.
Pour the batter into a greased baking pan lined with parchment paper.
Bake for 25-30 minutes. You will know when it is ready when a toothpick inserted into the center comes out clean with a few moist crumbs attached.
Let brownies cool before slicing. Dust with remaining espresso. Serve and enjoy!