You won't go far wrong with the NGK DCPR7E-N-10.
NGK stock code 4983.
They are OEM, Fiat sell them under part number 55188857 and 46823299 but are marked FCT and boxed for Fiat/Afla/Lancia.
You can often pick up these Fiat boxed ones cheap on that well known auction site.
If you've never swapped them before the plug caps can be a bit sticky and due to how they are sited there's not a lot to get hold of, so you might have to tug and jiggle a fair bit on one or two leads/caps.
The threads in the head are alloy and quite soft, so carefully start screwing in the new plugs by hand and only nip up with the wrench.
Due to the two different metals (plug body steal and head is alloy) a very small dab of copper grease smeared thinly on the new plug treads should help keep some electrolytic corrosion at bay.