Preheat oven to 475 F, and put oven rack as high as it will go. Spray a baking sheet with non-stick spray.
Wash squash and cut off stem and flower ends.
Cut each squash into quarters lengthwise, then cut into pieces about 2 inches long.
Combine olive oil, lemon juice, mint and salt ; then put that mixture into a plastic bowl and toss squash with the mixture.
Arrange squash on roasting pan, in a single layer as much as possible. (I would recommend using two baking sheets if it seems really crowded.)
Roast squash, turning every 15-20 minutes, until slightly browned and cooked to your liking. I turned my squash twice, with a total cooking time of 45 minutes, but I would start checking after 35 minutes.
When the squash is done, put it back into the same bowl and toss with the Feta cheese.
Season with fresh-ground black pepper to taste. This can be served hot or at room temperature.