Pre heat your oven to 180°C and line 2 baking trays with baking paper.
Melt 100g of your dairy free milk chocolate on the hob. Leave to cool.
Whilst the chocolate cools, whisk together your dairy free butter, light brown sugar, caster sugar and vanilla for a few minutes until creamy.
Add your melted chocolate and egg to the mixture and whisk again until combined.
Sift in your self raising flour and cocoa powder. Mix well.
Break up your chocolate into large chunks (75g dairy free milk chocolate and 75g dairy free white chocolate). Stir into the mixture.
Using about a tablespoon of mixture per cookie, roll into balls and place spaced out on your baking tray. The mixture will make around 12 (6 per tray).
Bake in the oven for 10 minutes. The cookies will still be soft but will firm up as they cool.