Preheat the oven to 350ºF and line a large baking sheet with parchment paper. Using a mandolin slicer or sharp knife, cut the parsnip into paper-thin slices. The thinner they are, the crispier they will be. (For larger chips, cut the parsnip on a diagonal. The slices will shrink as they cook!)
Place the parsnip slices on the prepared pan and drizzle with the olive oil. Toss well, and rub the oil into the slices so they are evenly coated. Arrange them into a single layer without overlap (use two baking sheets if you need to) and sprinkle the tops with salt. Bake at 350ºF for 15 minutes.
When the timer goes off, pull the pan from the oven and remove any thinner pieces that are already brown and crispy. Flip the slices over, and return to the oven for another 5 minutes. At this point, more slices should be crispy. If you have a few pieces that still need to cook longer, they can bake for another 4 to 5 minutes. Let the chips cool completely on the pan, then they are ready to serve. Leftovers can be stored in an airtight container in the fridge for up to 5 days. (See notes for tips.)
Notes
Nutrition information is for 1/4 of the batch, or roughly a 1/2 cup of cooked chips. This is just an estimate, not a guarantee.Leftover chips will not be as crispy the next day, but you can crisp them up in the oven again at 350ºF for 5 to 10 minutes. Let them cool completely before serving.