Preheat oven to 150°C (300°F). Place the eggwhite in the bowl of an electric mixer and whisk until stiff peaks form. Gradually add the sugar, whisking well, until mixture is stiff and glossy. Add the cornflour and vinegar and whisk until just combined. Spoon into 12 x ½ cup-capacity (125ml) muffin tins lined with cupcake papers+. Reduce oven to 120°C (250°F) and bake for 1 hour. Turn the oven off and allow the pavlovas to cool completely in the oven. Carefully cut the pavlova tops off, fill with cream and sandwich with tops. Serve immediately with liqueur. Makes 12.
+ If you have an ice-cream scoop, use it to scoop the mixture into the cupcake papers to get a lovely round shape