Cook the wild rice blend according to the package directions.
Preheat the oven to 400ºF. Line a baking sheet with parchment paper. Add the butternut squash to the baking sheet and toss with 1 tablespoon of olive oil and salt and pepper, to taste. Roast for about 30 minutes or until tender.
In a large skillet, heat the remaining 2 tablespoons of olive oil over medium heat. Add the onion, celery, and mushrooms. Sauté for about 5 minutes. Add the garlic and herbs. Sauté for another 2-3 minutes. Season to taste with salt and pepper.
In a large bowl, combine the cooked rice, roasted squash, sautéed vegetables, cranberries, walnuts, and parsley. Toss to combine. Season to taste with salt and pepper.
Serve immediately or transfer to a casserole dish, cover, and refrigerate for up to 3 days. To reheat, bake, covered, in a 350ºF oven for about 20 minutes.