Preheat your oven to 170°C and grease or line a 20 x 20cm baking tin with baking paper.
In a mixing bowl, whisk together the fat free Greek yoghurt and eggs until smooth and creamy.
Add the xylitol and vanilla essence, mixing well to combine.
Gently fold in the sifted cocoa powder until the batter is thick and lump-free.
Pour the mixture into your prepared tin and smooth the top evenly.
Bake for 30–35 minutes, or until set but still slightly soft in the center.
Allow to cool completely at room temperature, then chill in the fridge for 2–3 hours for the perfect fudgy texture.
Slice into 9 squares and serve.
