Preheat the oven to 425 degrees F. Set out a large rimmed baking sheet.
Peel the parsnips and slice them into ½ inch rounds. Cut the largest pieces in half.
Place the parsnips on the baking sheet. Drizzle the parsnips with olive oil. Toss to coat, then spread them out on the baking sheet. Generously sprinkle the parsnips with salt and pepper.
Bake for 25-30 minutes, until fork-tender.
Meanwhile, mince the garlic and chop the parsley. Mix them into the melted butter.
Once the parsnips are soft, pour the garlic butter over the top. Toss the parsnips and bake another 3-5 minutes. Serve immediately.