Rinse quinoa, pour in a saucepan with 2 cups of water and bring to a boil. Avoid stirring and let boil until the quinoa absorbs all the remaining water, about 10 to 15 minutes. Set aside in a large mixing bowl.
Heat about a tablespoon of oil in a pan. Add the garlic, onions, butternut squash and celeriac to the oil. Cook on medium, stirring frequently, until veggies are fork tender, about 20 minutes. Once the veggies are softened, add the thyme, sage, salt and pepper and stir coat evenly.
Add the veggies to the quinoa in a large mixing bowl and stir to combine. Mix in chopped parsley, hazelnuts and olive oil and toss until everything is evenly distributed.