Have 2 rectangular plastic ice-cream containers ( size 11 inches by 4 inches with a depth of 4 inches - cut 2 strip's of baking parchment paper off and then rinse both of them under the cold water tap - clinch with palm of hand too get rid of excess water and then place each one in the identical plastic containers. Share the marshmallows in each of the 2 plastic containers

Boil a bit of cold tap water in a large saucepan or one's casserole cooking dish. Place the 250g block of butter in a very large metal mixing bowl or large cooking glass bowl and then add the blocks of milk chocolate and then the Lyle's Golden Syrup. Once it's all melted - stir with a wooden spoon and then roughly crumble shop bought biscuits into the mix - break them up with your fingers

Add equal amounts of the mix to each rectangular plastic container. Press down with a dessert spoon and then store the 2 plastic containers in the fridge, for at least a day. Once set - is able too cut a piece off - with a sharp kitchen knife. Should be possible too easily pull out the homemade brown chocolate fridge cake, because it was lined in pieces of baking parchment paper