Preheat the grill to approximately 375–400°F (190–205°C) and clean the grill grates.
Cut the bread into approximately 1-inch-thick slices.
Combine the softened butter, garlic, Parmesan, parsley, olive oil, salt, and black pepper.
Spread the garlic butter generously over both sides of each bread slice.
Place the bread directly onto the grill.
Grill for approximately 1–3 minutes per side, watching carefully, until golden and lightly charred.
Remove from the grill and finish with additional Parmesan and parsley if desired.
Serve immediately while warm and crisp.