Pre-heat the oven to 170°C (325°F) and prepare an 8x8 inch tin by lining it with grease-proof paper or by greasing.
Slowly heat the chocolate and butter in a pan until just melted, then add the coffee. Leave to cool for about 10 minutes.
In a large bowl, whisk the sugar with the eggs, then add in the vanilla and cooled chocolate mixture.
Sift the flour and cocoa together and stir into the wet ingredients until combined.
Pour into the tin and bake for around 20-25 minutes (until an inserted skewer comes out clean).
Remove from the oven and allow to cool completely. If you have the time, let the brownie sit in the fridge over night.