Mix all of the dry ingredients for the concrete into a bowl. Melt the butter then pour it into the dry ingredients and mix in - use your fingers to rub it together until it resembles a crumble topping mixture

Combine the cornflour, sugar, food colouring and extract in a bowl. Add a little of the milk to make a paste. Pour the rest of the milk into a saucepan and gently heat until hot but not boiling

Once it's hot, pour into the pink paste, whisk to combine and then pour it all back into the saucepan. Keep stirring with the whisk until the mixture just comes to boil and thickens to a nice custard consistency, this won't take long. Once thickened remove from heat and pour over your chocolate concrete