I very successfully made your No Churn Pomegranate Ice Cream (Nigella Express, p132) last week but wanted a second non alcoholic flavour, so I tried orange and chocolate. I used roughly the same amount of orange juice as the yield from my pomegranates, added about 100g of melted milk chocolate, which I swirled in and added some chocolate chips too. The flavour was quite nice but the texture was all wrong - slighty crumbly rather than soft and silky like the pomegranate one. Where did I go wrong and what can I do next time to get the texture right whilst still allowing me to play with other flavours?
When making ice creams, including the no-churn type, the texture and freezing qualities are determined by the ratios of fat, sugar and other liquids (such as juice or the water content of items like milk and cream). If the ice cream has too little fat then it will be icy and hard, if it has too much sugar then it will not freeze very well. Unfortunately adding the melted chocolate to the basic ice cream mixture has changed this balance, and the cocoa solids in the chocolate will also have affected the texture of the ice cream - it is probably the cocoa solids in the chocolate which have caused the crumbly texture.
If you are experimenting with flavours then you need to stick to the basic quantities of juice and cream in the Pomegranate Ice Cream Recipe and you can probably add a little more sugar if it is needed (remember that the ice cream will taste less sweet once it has frozen). Alternatively Nigella has a no churn Bitter Orange Ice Cream in Nigella Bites (p70). If you do want to add some alcohol to your ice cream then we would suggest limiting it to no more than 45ml (3 tablespoons) of regular spirits per 500ml (2 cups) double (heavy) cream (if you using a lower alcohol liqueur like Malibu then you can add a bit more).