Step 1: Preheat oven to 375°F (190°C). Arrange the halved or quartered heirloom tomatoes cut-side up on a large baking sheet. Drizzle generously with olive oil, then season with salt and freshly cracked black pepper. Scatter fresh thyme sprigs and crushed rosemary needles over the tomatoes.
Step 2: Roast for 25-35 minutes, or until the tomatoes are tender, slightly shriveled, and caramelized around the edges. Keep an eye on them to prevent burning. Remove from oven and set aside.
Step 3: While the tomatoes are roasting, prepare the garlic confit. In a small, heavy-bottomed saucepan, combine the peeled garlic cloves with 1/2 cup of extra virgin olive oil, ensuring the garlic is fully submerged. Add the bay leaf and black peppercorns (if using).
Step 4: Heat the saucepan over very low heat. The oil should barely simmer, with small bubbles gently forming around the garlic. Cook for 20-30 minutes, or until the garlic cloves are golden brown and very tender when pierced with a fork. Do not let the garlic fry or brown too quickly.
Step 5: Carefully transfer the roasted heirloom tomatoes to a serving dish. Using a slotted spoon, gently spoon the confit garlic cloves over the warm tomatoes. Drizzle a generous amount of the garlic-infused olive oil from the confit pan over the dish.
Step 6: Finish by scattering fresh basil leaves over the tomatoes and garlic. Add another sprinkle of flaky sea salt and a grind of fresh black pepper. For an extra touch, drizzle with balsamic glaze if desired. Serve warm or at room temperature.