To prepare the raspberry and elderflower syrup, place the raspberries and elderflower cordial in a small bowl. Using a fork, mash the raspberries to make a thick, pulpy sauce. Strain through a fine mesh sieve. Cover and refrigerate until required.

To serve, pour 1 tablespoon of the syrup into a champagne glass. Top with champagne. Garnish with a couple of fresh raspberries.

Drink immediately.