Preheat oven to 160 degrees celsius (fan-forced). Grease and line a 20cm square baking tin with baking paper and set aside.
Melt the dark chocolate and butter in the Thermomix for 3 minutes, Speed 2, 80 degrees.
Add the vanilla extract, salt, almond meal, eggs, brown sugar and cocoa powder and mix together on Speed 5, 10 seconds. Scrape down the sides of the bowl and repeat for a further 10 seconds.
Pour into the prepared baking tin and bake for 30-35 minutes or until a crust has formed on the top and the brownie feels slightly firm (do not overcook).
Allow to cool completely in the tin before turning out and cutting into slices.
Store in an airtight container at room temperature for up to 5 days (or freeze for up to 1 month).