Juice two of the pomegranates** and the lime and strain the juices into a large bowl. Save the third pomegranate to use the seeds before serving.
Sift in the icing sugar and whisk to dissolve. Feel free to use the whisk attachment of your stand mixer, or use a hand mixer or electric whisk - just be careful as the juice will splatter and can stain!
Add the double cream to the pomegranate mixture and whisk, using your preferred method, until soft peaks form. If you're going to use this as frosting, stop here and frost your cake or cupcakes and serve immediately.
Transfer the pomegranate whipped cream to an airtight freezer-safe container and freeze at least 4 hours or overnight.
Remove from freezer 15 minutes before serving to soften, then serve in pretty bowls and scatter with seeds from the third pomegranate.