A Greek salad can be many things, and this arugula salad is a delicious cool weather treat, especially when winter squashes are in season. You can swap out the butternut for calabasa or delicata, or any other yellow squash of your liking. Experiment! You can also swap out the greens. This would be equally delicious with baby spinach. Using Greek feta is important though. Greek feta is a protected designation of origin cheese and is always made with either sheep’s milk or a combination of sheep’s and goat’s milk.