75g caster sugar
Heat the oven to 170C fan oven/180C/350F/Gas 4. Removing the rubber seal from a 1/2 litre Kilner jar, place it in the oven for 5 minutes to sterilise then leave to cool. Place half the blackberries in the base of the jar and scatter over a third of the sugar. Layer the raspberries on top, scattering over another third of the sugar, then fill the jar with the remaining blackberries and scatter over remaining sugar.
Pour over the vodka and gently press the fruit to submerge it. Slip the rubber seal into place and clip the jar shut. Place in a cool, dark place for several months. I turn it upside down once in the first 24 hours to encourage the sugar to dissolve, and then right it again a few hours later. As well as serving it with ice-cream, the liquor is good for sipping when the first winter cough strikes.