Preheat the oven to 375ºF. Line 2 baking sheets with parchment paper.

Toss the garlic, parsnips, carrots, sweet potatoes, turnip, and rutabaga in a large bowl with the oil. Add the garlic powder, onion powder, and salt. Toss to combine. Spread the vegetables out on the baking sheets. Bake for 30-45 minutes until the vegetables are tender.

Transfer the roasted vegetables to a food processor fitted with the steel blade. Add the ghee or butter. Process until smooth. Add additional salt to taste if desired. (Alternatively, you can mash the vegetables using an electric mixer.) Serve warm.