Preheat your oven to 180C/160C fan.
Line a 8"x8" baking tin with parchment paper.
Melt the 100g of chocolate in a bowl either in the microwave or over a pot of gently simmering water.
Once melted, set aside to cool slightly.
To this chocolate add the yoghurt and sugar, then mix to form a a smooth mix.
Sieve in the flour, cocoa, salt and soda, then mix.
To this add the milk and mix to form a smooth batter.
Spoon this brownie mix into the prepared tin and level out.
Finally sprinkle the 150g of chocolate on top and place in the preheated oven for 25 minutes.
Remove and allow to cool before portioning.
Sprinkle with fresh raspberries when serving and enjoy!
