You can add booze or increase the sugar content. That makes it softer, although it might be problematic for a diabetic. Other than that, dilute the cream with semi-skimmed milk, or use single cream and semi-skimmed milk. These creams have lower butterfat content and tend to freeze less firmly. Oh, and you don't warm the egg yolks first.. Just heat the milk or milk and cream mixed with the vanilla pod. Mix the sugar or sweetener with the yolks. Add the hot milk and cream to the eggs and sugar and return the whole lot back to a clean pan. If you don't use a clean pan, you run the risk of scorching the custard. Stir over gentle heat til thickened. Cool, then proceed with whatever recipe you're using.