Potato, pumpkin and sage gratin

1.Preheat oven to 200°C (180°C fan-forced). Grease a shallow 2-litre (8-cup) rectangular ovenproof dish. Place on a baking tray. Place potato in a large microwave-safe dish. Cover; microwave on high (100%) for 5 minutes or until just tender. Stand for 2 minutes. Drain. Repeat with pumpkin; microwave for 3-4 minutes. Stand for 2 minutes. Drain.

2.Meanwhile, stud onion all over with clove and place milk, cream and onion in a medium heavy-based saucepan over moderate heat. Bring to a simmer. Remove from heat. Stand for 5 minutes for flavours to infuse. Using tongs, remove and discard onion. Pour milk into a heatproof jug. Wipe pan clean. Melt butter in same pan over moderate heat. Add flour; cook and stir for 1-2 minutes or until bubbling. Add nutmeg; cook and stir for 30 seconds or until fragrant. Gradually whisk in warm cream mixture until smooth. Cook and whisk for 4 minutes or until sauce boils and thickens. Remove from heat; stir in half the parmesan until melted and smooth. Season.

3.Arrange half the potato over base of prepared dish. Top with half the pumpkin; pour over half the cream mixture. Repeat layers. Sprinkle with remaining parmesan and the cayenne pepper. Bake for 30-35 minutes or until bubbling and golden. Stand gratin for 5 minutes.

4.Melt extra butter in small frying pan over moderate heat. Add sage; cook and turn for 1-2 minutes or until crisp. Drain on paper towels. Serve gratin topped with sage.