Preheat oven to 425 degrees.
In a large bowl, toss the squash with the olive oil and salt. Spread on a sheet pan and roast, tossing once or twice, starting on the bottom rack and moving to the top halfway through, until very golden, about 25 to 30 minutes.
While it’s still warm, scrape the squash into a serving bowl, and sprinkle with the olives, orange juice, zest, and parsley.
Toss well. Sprinkle the chopped walnuts on top, and serve.