Can I cook with nearly ripe butternut squash? Due to a frost I had to bring in a few not-quite-ripe butternut squash.  The greenish markings on the outside and the not-well-developed seeds are signs they are not as ripe as desirable.  Can I still cook with these? Note they were photographed on a green cutting board but the color of the squash is close to true.
Unripe winter squash taste different from ripe, but you can treat unripe, peeled butternut like summer squash with good results.

My personal preference is to pluck any later flowers rather than let unripe fruit develop. These can be eaten raw or stuffed and cooked (my go-to method is seasoned cream cheese and chive).