Place the quartered onions on the baking sheet, being careful to keep the wedges intact. Drizzle the onions with 2 tablespoons oil, season with salt and pepper, and gently turn the onions to coat, again being mindful of keeping the wedges intact. Roast the onions, turning occasionally, until softened and slightly caramelized, 30 to 45 minutes, depending on the size of your onions.