Step 1

Set up a grill for cooking with direct and indirect heat. If using a charcoal grill, build the coals on one side only. If using a gas grill, heat one side only.

Step 2

To a small saucepan over the indirect-heat side of the grill, add the garlic cloves and olive oil. Close the lid of the grill and gently simmer until the garlic cloves are roasted and soft, 12 to 15 minutes. Remove from the heat and, using a fork, mash the cloves to form a coarse paste. Add the butter, garlic powder, salt and pepper. Mix well to combine.

Step 3

Lay the bread out on a sheet tray, cut-side up, and spoon all but 2 tablespoons of the garlic mixture over the bread. Add 1/2 cup grated Parmesan to each half. Place the sheet tray on the indirect-heat side of the grill, then close the lid and bake until crisp and the cheese has set, 3 to 5 minutes.

Step 4

Remove from the heat, then put the 2 halves of the bread together on a piece of foil. Spoon or brush the remaining garlic butter over the top. Wrap in the foil, then place on the indirect-heat side of the grill. Close the grill and bake until golden brown and the garlic butter has soaked into the bread, another 3 to 5 minutes. To serve, open the foil, cut into smaller pieces and place on a board or platter.