Slow Cooked Bell Peppers with Mozzarella

​1 lb. any color bell peppers, halved, seeds and ribs removed
½ head of garlic
½ cup extra-virgin olive oil
¾ tsp. kosher salt
1 Tbsp. balsamic vinegar
2 mozzarella balls, sliced
Fresh basil, for garnish

Place a rack in middle of oven and preheat to 350°. Toss bell peppers, garlic, oil, and salt in a shallow 2-qt. baking dish to combine. Turn garlic cut side down, then roast vegetables, tossing 2 or 3 times, until golden brown, very tender, and edges are crisp, 80–90 minutes. Let cool slightly, then add vinegar and toss to coat. Place sliced mozzarella onto a serving plate, top with peppers, and drizzle with the oil and vinegar in the baking dish. Serve with fresh basil.