If refrigerated, you may reheat the tart in the oven (at 400°F for ~5 minutes) or on the stovetop in a skillet (on medium heat for ~5 minutes). You may reheat along with the raw tomato slices on top or remove before reheating and place them back on. If tomato tart is frozen, let it thaw at room temperature for 30 minutes and reheat at 400°F for 12-15 minutes.