Making a flavoured butter is simply a matter of softening the butter and mixing it with your chosen flavouring (use less salt if the butter is salted, or no salt at all). I use a processor or blender for the mixing. To store the butter, lay out a piece of cling film and spoon the soft butter mixture on to it in a row of blobs. Then, roll up the cling film with the butter inside and mould it into a long sausage. Twist the cling film ends to secure it, then chill it in the fridge until firm. It will keep for a week or so, and you can slice off sections as you need. If you want to keep it longer, just pop it in the freezer and thaw it for 15 minutes before slicing and using. Or, slice the whole roll and freeze the slices laid out on cling film on a tray. When frozen, you can put them loose in a bag and keep them frozen, helping yourself to one or two slices as you need them.