Scrub the new potatoes, but do not peel them. Either steam them in a colander over boiling water covered with a lid, or boil them in lightly salted water. They will need 8-15 minutes depending on their size.
Melt the butter in a saucepan, add the washed garlic leaves and let them cook for a minute or two, turning them in the butter as they soften. Once they have wilted, pour in the cream, then bring it to the boil.
As the cream starts to boil, remove it quickly from the heat, season it lightly with pepper, the lemon juice and zest then cover with a lid or plate and set aside for 10 minutes for the cream and garlic to infuse.
Drain the potatoes and put them on a large serving plate. Using the back of a spoon or a potato masher, press firmly down on the potatoes to lightly crush them. Ideally the skins should be broken and the flesh open enough to take up the dressing, but not so heavily crushed that they fall to pieces.
Spoon the cream and softened garlic leaves over the potatoes, leave for a few minutes for the cream to soak in, then eat while still hot.