Preheat oven to 375°; spray pan with cooking spray. Place pears, cut side up, in prepared pan.
In small bowl, whisk lemon juice, 2 Tbsp butter, 1 Tbsp syrup, ¼ tsp cinnamon and cardamom; brush over pears and roast 35 minutes or until tender-crisp.
In food processor, pulse oats, and remaining 2 Tbsp butter, 1 Tbsp syrup and ¼ tsp cinnamon until small pieces remain; sprinkle over pears. Roast pears 35 minutes or until topping is golden brown and pears are tender.
Serve pears with ice cream sprinkled with pomegranate arils.