In Britten's "Deo Gracias" (from A Ceremony of Carols) there are a few sentences and words which I don't really know how to pronounce:
the appil take ben
that appil take was
In the versions I've seen there is an accent on the second 'e' of 'clerkes' and also on the 'e' of 'take', indicating that the letter should be pronounced (i.e. not silent as in modern English). 'Clerk' is of course pronounced 'clark' in British English.
As far as I know 'finden' is simply 'find' with an extra syllable added.
I'm sure there must be recordings on YouTube you could listen to.
I think the Middle English pronunciation is more or less like this:
[klerkəz fiːndən ðeː apːəl taːkə beːn ðat apːəl taːkə waz]
I don't know if this is how it is sung in Deo Gracias. I might have some errors since this is from my phone and I haven't looked it up yet, so this is by memory. From what I recall, the most uncertain parts are the voicing of word-final and word-initial fricatives and the presence of geminate consonants (they were simplified at some point in Middle English). I'm also not sure that the "i" in "finden" was lengthened yet. The vowel qualities are of course approximate: for example, Middle English short /e/ may have been mid-high, mid-low or true mid, as there is no phonemic contrast between these.