Grease and line an 20cm square baking tin with baking paper.
Place the butter (cubed), caster sugar and cocoa into your Thermomix bowl and cook for 3 minutes, 65 degrees speed 2. If the butter hasn’t quite melted, cook for a further 1 minute, 65 degrees, speed 2.
Add the vanilla extract, eggs and plain flour and mix for 10 seconds on speed 4 to combine
Scrape down the sides of your bowl and mix for a further 10 seconds on speed 4.
Pour into the prepared tin and bake for 30 - 35 minutes or until a skewer inserted into the middle comes out clean.
It’s important not to overcook this recipe, otherwise you won’t get a soft and fudgey brownie.
As tempting as it is, make sure you let the brownie cool completely in the baking tin before cutting, as this helps it to set.
If you don’t have any cocoa, you can also use cacao, this will give your brownies a richer flavour.
You can ice the brownies with a simple chocolate icing (recipe here) or leave plain.