Start by spatchcocking the poussins. Cut them along the backbone with a knife or scissors. Flatten them with the palm of your hand, then rub with the grated garlic and season generously all over with the cayenne pepper and sea salt flakes.
Heat the butter and oil in a large heavy based skillet or frying pan. Cook the poussins, cut-side down, over a medium heat for 3 minutes, then flip them over and cook the skin-side down for 5 minutes.
Lower the heat and put a circle of baking parchment or greaseproof paper over the poussins, followed by a smaller frying pan on top. Weight it all down with something heavy.
Cook for 20-25 minutes over the lowest possible heat. To test the poussins are cooked, pull away at the legs – they should come away easily and the juices should run clear.
Meanwhile, make the plum chutney, put the plums or greengages in a lidded saucepan. Add a splash of water, cover with a lid and boil over a medium-low heat for about 10 minutes until the fruits start to soften.
Mash the plums with a fork, then add the garlic, paprika and treacle. Season with sea salt. Cook with the lid off for another 10 minutes. Add the dill. You can keep the sauce for a few days in a sterilized jar in the refrigerator.
When the poussins are done, leave them to rest on a chopping board for 5 minutes. Add the herbs to the buttery juices in the pan and cook for a further minute or two.
Serve the Georgian poussins drizzled with the herby juices with the plum chutney on the side and some sourdough bread to mop it all up.