Preheat oven to 425°F and line a large sheet pan with parchment.
Arrange the split bread cut side up. Brush with olive oil, then rub or spread on the minced garlic.
Season the bread lightly with salt and black pepper, then toast for 5 minutes to crisp the surface.
Spread pizza sauce evenly over the toasted bread, reaching the edges for coverage.
Top with mozzarella, layer on the pepperoni, and sprinkle Parmesan, Italian seasoning, and red pepper flakes.
Bake until cheese is melted and edges are golden, about 7–9 minutes. Broil 1 minute for extra browning if desired.
Rest 2 minutes, shower with fresh basil, then slice and serve hot.