Preheat oven to 450°. Combine potatoes, carrots, and parsnips in a medium bowl. Add olive oil, salt, pepper, and garlic; toss well to coat. Arrange vegetable mixture on a rack placed in a broiler pan. Bake at 450° for 28 minutes, stirring after 10 minutes.
These vegetables are delicious. My entire family (even the 5-year-olds) loved them. I had never tried parsnips before, but they have such a great flavor. I thought the dish overall had plenty of flavor. The only thing I would caution people to do is to watch it carefully so the parsnips and carrots don't get over-done. Great way to eat veggies in the winter.