Cut the top third off the head of garlic, exposing the tops of the garlic cloves. Put on a piece of aluminum foil, drizzle with 1 tablespoon of the oil and sprinkle with 1/4 teaspoon each salt and pepper. Wrap tightly and roast until the cloves are golden brown and very soft, about 45 minutes; cool slightly.
Unwrap the garlic and pour any garlic-flavored oil from the foil into a small bowl; squeeze the roasted cloves into the same bowl, discarding the papery shells. Add the remaining 2 tablespoons oil and mash with a fork until smooth; season with additional salt and pepper.
Put the bread halves on a baking sheet and evenly spread with the roasted garlic mixture. Top with the Parmesan and a few grinds of pepper. Bake until the bread is toasted and the cheese is melted, about 10 minutes. Sprinkle with parsley and cut into pieces.
Copyright 2016 Television Food Network, G.P. All rights reserved.