I tried to make the No-Churn Salted Caramel Bourbon Ice Cream but I noticed that the ice cream starts to form some lumps when I'm mixing the whipped cream with the caramel mixture. I'm using double cream instead of heavy cream. I whipped the double cream till stiff peaks but once I start folding it with the caramel mixture lumps start to form. How can I solve this problem?
Nigella's No-Churn Salted Caramel Bourbon Ice Cream from AT MY TABLE) mixes store-bought canned caramel or dulce de leche with whipped cream. In the UK you can just whisk the caramel and double cream together, as the high fat content of the double cream means that the mixture will whisk without any problems.
In the US heavy cream has a lower fat content than double cream and doesn't whisk as well, particularly when other ingredients have been added. So for the no-churn ice cream recipes in Nigella's US books we tend to adapt the recipes by whisking the cream first and then adding any other ingredients. We would mention that the cream should only be whipped until it is billowy and has just reached soft peaks, even if it is heavy cream. We suspect that the lumps are appearing as the cream has been whisked until stiff and then when you stir it further the fat in the cream will start to clump together, forming buttery lumps. If you are using double cream we would suggest putting the cream and caramel into a bowl and just whisking together, following the method from the recipe link above.