This one is an optional step, but is very useful: chill the mixing bowl for 10 minutes in the freezer! I do this whilst I prepare the other ingredients: measure out the cream, open the tin of condensed milk and sift the cocoa (the last step is useful to avoid lumps of cocoa in the finished ice cream).
Once the bowl has chilled, remove it from the freezer and pour in the double cream. Beat with a handheld electric mixer until the cream starts to thicken.
500 ml (2 cups + 1 tbsp) double (heavy) cream
Tip in the condensed milk and sprinkle over the cocoa. Continue beating until the mixture is evenly combined and has thickened.
397 g (14 oz) condensed milk, 40 g (¼ cup + 2 tbsp) cocoa powder
Transfer the mixture into a freezer safe container and pop in the freezer for at least six hours, ideally overnight. When you're ready to indulge, simply remove the ice cream from the freezer about 5 minutes before serving, to allow it to soften slightly, making it easier to scoop. Enjoy!