Put the fruit and the elderflower cordial into a medium sized pan. Bring to the boil, cover, reduce the heat and simmer for about five minutes until the berries have softened.
Remove the lid, increase the heat and boil for a minute to reduce the liquid a little. Transfer to a bowl and allow to cool.
Using a small hand whisk mix the clotted cream and milk together in a small bowl until slightly thickened.
Fold in two thirds of the cooled blackberry mixture. Spoon into two glasses and pour the remaining fruit mixture on top.