Lie a clean tea towel out on the counter and spread the natural yogurt over it. Leave for 30 minutes, until all the excess liquid has been absorbed.
After 30 minutes, scrape the yogurt off a tea towel into a bowl. Stir in the cocoa powder, brown sugar and Kahlua, if using.
In a tiny egg cup-size bowl, stir the instant coffee into the water until it dissolves. Stir this into the yogurt until totally combined.
Place the yoghurt inside a sealed container and leave in the freezer for at least 8 hours to set. If you remember, stir the yogurt every hour to ensure ultra-creaminess.
Remove the frozen yogurt from the freezer 30 minutes before ready to serve to allow to soften up. Scoop into bowls and top with dark chocolate chips before serving.
This recipe doesn't use an ice cream maker. But if you would like to use yours, after step 3, place the frozen yogurt mixture into the ice cream maker and leave to churn for 30 minutes before you place it in the freezer.