EASA, being European and therefore knowing everything as well as being morally and intellectually superior to America, do not recognise FAA STCs.
Somebody has to generate an EASA STC, and this has to be specific to the aircraft type.
In the UK, I think Lees Avionics is the main firm which generates these STCs and (as well as doing their own installations) they sell the paperwork packs to most of the other UK avionics shops.