Start by making the fruit base. Pour 60ml water into a saucepan and add the caster sugar, if using (use 75ml water if not using the sugar), and tip in the berries. Cook for 3-4 mins over a medium heat until the berries have defrosted and are starting to soften, and the liquid is bubbling. Turn off the heat and leave to cool. Strain and pour into a jug.

Pour the fruit base (you should have approximately 80ml) into a cocktail shaker with the vodka, raspberry liqueur, blue curaçao, lemon juice and a large handful of ice. Shake well until the outside of the shaker feels cold and frosty.

Double strain into four chilled coupe or martini glasses. Sprinkle with a little edible glitter, if using, and stir. Garnish with a skewered cocktail cherry, too, if you like.