Well, my research into this daydream -- working as a nurse in Spain -- is quite disappointing. Spain has an overabundance of nurses and there are not enough jobs. They are not in need and not giving out work permits or visas. Sheesh.
There are quite a few places I would like to live in Spain. I speak South American Spanish but do understand (and am understood by) Spanish speakers from Spain.
Mallorca is one, and there is an english-language agency there that provides in-home care. This is not really my area of interest, but one possibility.
Midwifery is another area in which there is a need. Again, not what I hope to specialize in, but ...