2Slice the tips off the garlic bulbs, drizzle with oil, and wrap in foil.
3Make thin slices in potatoes, leaving the bottom intact. Toss with olive oil, salt, and pepper. Space cut-side-up on the baking tray, brushing with excess oil.
4Add garlic bulbs to the tray and roast for 30 minutes. Brush with excess oil, then roast for another 15-20 minutes, or until golden and crispy.
5Squeeze roasted garlic into a bowl. Combine with butter, parsley, salt, and pepper.