I pick these young, usually about 2 foot long, and while they are still a pale green. If left on the vine they will thicken and grow to a pale beige, but I like them young and tender. I've read that the older squash can be eaten much like any winter squash, baked or stuffed, but we haven't allowed any to get that old. There's a different texture to these squash that is very pleasant, nutty and buttery. Really, really delicious. Trust me!
These make a delicious and different addition to the garden - a conversation starter for sure. Here are a few pictures of my Tromboncino from the past few years so you can see how they progress in the garden.
just beginning to form
a bit older
a few harvested squash