Toss the Brussels sprouts and the butternut squash in the olive oil and season with salt and pepper. Arrange on a baking sheet in an even single layer.
Roast until the squash is tender and the Brussels sprouts have slightly caramelized on the underside, about 20 minutes.
For the maple tahini dressing:
Add the tahini, maple syrup, vinegar, lemon juice, Dijon mustard and garlic to the bowl of a food processor fitted with the blade attachment.
Pulse until the ingredients are combined then slowly add the olive oil with the food processor running. Season to taste with salt and pepper and set aside until ready to use. If making in advance then store, refrigerated, in an airtight container.
For assembly:
In a medium saucepan over medium heat bring the chicken stock to a boil.
Add the quinoa and farro, and cook on medium-low heat until the broth is absorbed and the quinoa is tender, about 20 minutes. Fluff the grains with a fork and set aside.
Add the arugula, grains, roasted vegetables, apple and hazelnuts to a large salad or mixing bowl. Drizzle with ¼ of the dressing, tossing to combine and adding more dressing if needed. Serve.