Hola Garry

the adjective "blandurrio / a" comes from "blando" (soft) - so here, you need to dip the bread in the milk but not overdo it, because if you do, they won't just be "wet" (empapadas) but "too soft" (blandurrias) 

Sometimes we add this suffix (also -orro, -orrio)  with a negative connotation, to make that adjective "worse".

Blando /a  is fine, just soft, but blandurrio / a would have that negative connotation of "too soft, not nice, difficult to eat etc".

I would have personally used "blandengue" in this case, but suffixes are used in different ways in different parts. 

Saludos