Allow the butter to come up to room temperature and soften. Rinse the leaves and then either give them a good whizz in a salad spinner or drain and pat dry with a kitchen towel.

Chop the leaves as finally as you can, then beat into the butter along with the salt, pepper and zest. You may find some moisture comes out of the leaves and separates slightly; if so just soak it up with a little more kitchen paper.

Spoon the butter out onto a piece of cling film into a rough sausage shape, then fold the sides of the cling film up so it is wrapped up.

Roll the sausage backwards and forwards a few times so it becomes a nice even log, then set in the fridge to firm up.

Unwrap the cling film then roll the butter in a sheet of greaseproof paper.

The butter will keep for two weeks in the fridge but can be stored in the freezer (wrapped in cling film) for up to six months, so you can just slice off a piece when you need it.