Preheat the oven to 400°F Lightly oil a rimmed baking sheet.
Scrub the winter squash and peel it , if desired; otherwise keep skin on. Halve the squash through the stem end and scoop out the seeds. Cut the halves horizontally into 1/2" slices. Small squash give you nice crescents, but if the squash is large, cut the slices into halves or thirds. In a large bowl, toss the squash pieces with the oil. Lay the squash out on the prepared baking sheet about 1/2" apart, and sprinkle with salt. Bake until easily pierced with a fork, about 20 minutes. Remove from the oven and set aside to cool.
While the squash bakes, spread the pepitas out on a small baking tray and, if they are not already salted, sprinkle with salt. Toast in the oven for about 5 minutes, or until somewhat puffed and crunchy. Set aside to cool.
Slice or cube the cheese. Quarter the pears lengthwise, remove the core, and slice thinly. To keep the cut surfaces of the pears from turning brown, sprinkle them with lemon juice. Make the dressing (see instructions below).
On a large platter or individual plates, make a bed of the greens. Arrange the roasted squash, pear slices and cheddar on top. Drizzle on the dressing and sprinkle with the toasted pepitas and cranberries.
To Make the Pear-Thyme Dressing: Core the pear and cut it into chunks, no need to peel it.
Put the pear, thyme, water, vinegar, salt and black pepper into a blender and puree. With the blender running, slowly pour in the oil.
Taste, and add mustard and honey or maple syrup, if desired.