Tip the blackberries, cinnamon stick, bay leaf and sugar into a large sterilised jar. Pour over the vodka, seal the jar and swirl around to dissolve the sugar. Store in a cool, dark place and turn the jar once a day for the first week.

After two to three weeks, strain the vodka through a fine mesh sieve (see tip, below) and decant into bottles, then label. It will keep its colour for a few months, and will be drinkable for up to a year. Use the infused blackberries in bakes or meringue-based desserts.