This dish is a home invention that's evolved over the years, a hybrid of Italian and French ingredients and techniques that's easy to put together as a midweek staple.
My wife had been cooking a version of this for years: chicken, mushrooms, garlic and onion cooked down together, finished with crème fraîche to bring the whole pan together into a sauce. No pasta shape, just a dependable dinner that came together fast on a weeknight.
It worked as a dish in its own right, and nothing about it needed fixing. It's evolved over a number of years since, picking up ideas from different places along the way, but that original version is still the base underneath everything.
The basil paste came from watching a Jamie Oliver cooking programme, where he bashed basil with a pinch of salt in a mortar instead of chopping it with a knife. It's essentially a fresh pesto, made the way it's done in Liguria: crushing the leaves rather than slicing them breaks down more of the leaf structure, so more of the oil and colour ends up in the paste instead of staying locked inside a neat chop. It changed the flavour of the dish completely, and the colour changed too, a much deeper, darker green than a knife had ever given it.
Slicing the chicken thin meant it cooked faster and picked up more of the garlic and onion from the pan instead of steaming quietly on its own, and it worked better against tagliatelle too. The crispy prosciutto was the last addition, fried separately in its own pan until properly brittle, left to cool and harden on kitchen paper, then placed on top at the end so it stays crunchy against the soft pasta. Everyone breaks their own piece into their pasta, which is a satisfying way to serve it.
Most creamy Italian-style pasta leans on double cream or mascarpone, both rich and fairly mild, and either would work here without much trouble. This dish never went that way. Crème fraîche has been in it from the start, and it's stayed that way rather than getting swapped for something more conventional along the way. Crème fraîche is cultured, so it carries a bit of tang alongside the fat, and it's lighter than cream or mascarpone by weight, which matters if this is going into a regular midweek rotation rather than an occasional treat.
In a hot pan that tang keeps the sauce from tasting flat the way an all-cream sauce sometimes can, and the lower fat content means the dish sits a little less heavily than it otherwise would. It also needs a bit more care over heat than mascarpone does, since it can split if the pan's left too hot for too long, so it goes in toward the end rather than at the start.
None of this adds up to one single tradition. The basil technique traces back to Liguria, the crème fraîche is French, the prosciutto is Italian, and a creamy chicken pasta like this one is closer to what's become an everyday dish in British kitchens than anything you'd find on a menu in Italy. Tagliatelle itself is a ribbon pasta from Emilia-Romagna, which at least keeps the pasta shape genuinely Italian even if not much else on the plate agrees with it.
It's built the way a lot of home cooking gets built: one part kept because it already worked, and a couple of ideas picked up wherever they turned up, in this case from a TV cooking segment rather than a family trip or a cookbook. There's nothing unusual in that. Most dishes that end up on a family table regularly got there the same way, through small changes made by whoever was cooking that night, not through anyone trying to recreate something they'd read about.
No. It combines an Italian pasta shape and cured ham with a French dairy product and a basil technique associated with Ligurian pesto, but the dish itself was put together at home rather than following one country's tradition.
Bashing it in a mortar with a little salt breaks down more of the leaf than a knife does, releasing more of its oil and colour into the paste. It's the same idea behind traditional Genovese pesto, just without the pine nuts or cheese.
It's lighter than both and carries a natural tang that keeps the sauce from tasting flat. It also holds up reasonably well over heat, as long as the pan isn't left to boil hard.
Yes. Prosciutto is dry-cured and crisps up thin and brittle, while pancetta is cured belly and gives a chewier, fattier crisp. Either works well scattered over the top.