150g vegan cookiesof your choice (we used Oreos), broken into chunks
Oreos do not contain any animal products in their ingredients list, however they aren’t made in isolation so there is a possibility they could contain trace amounts of milk from contact with other products.
Heat oven to 170C/150C fan/gas 3 and line a 18 x 30cm brownie tin with baking parchment. In a bowl mix together the flour, sugar, cocoa and ½ tsp salt. In a jug mix together 125ml water with the vanilla, oil, vinegar and yogurt. Pour the wet ingredients into the dry and mix until smooth and combined.
Pour the mix into the tin and smooth the top. Push the chunks of vegan biscuits into the batter, leaving some poking out of the top. (We used Oreos, which are made with dairy-free ingredients, although be aware that allergy information indicates that these may contain traces of milk.) Bake for 30-35 mins, until set but still squidgy in the middle. Leave to cool in the tin, then cut into squares.