Preheat the oven to 425ºF/220ºC and line a baking sheet with parchment paper.
Toss the butternut squash cubes with olive oil, ground cinnamon, ground cumin, ground ginger, kosher salt, and black pepper.
Arrange the seasoned squash cubes into a single layer on a rimmed sheet pan lined with parchment paper. Bake for 20 minutes, stir the squash then bake for another 20 minutes or until fork tender.
Add all the dressing ingredients to a blender. Blend until smooth and season to taste with kosher salt and freshly ground black pepper. If your apple is more tart, add one to two teaspoons of maple syrup.
In a small bowl, stir the sliced onions, rice vinegar, sugar, and salt until combined. Set aside.
Add the greens to a large salad bowl. Top with the roasted butternut squash, quick pickled sliced red onion, feta, and walnuts. Pour the dressing over, toss to combine, and serve immediately.