Rub the pear halves with the oil and place cut-side down on the grill. Grill until tender and soft and grill marks appear, about 20 minutes. Transfer to a serving plate.
In a small bowl, combine the honey, cardamom, cinnamon, and salt; mix well. Drizzle over the pears. Garnish with the macadamia nuts and, if desired, basil. Serve warm.