Sweet potato, turnip and wild mushroom gratin

1. Step: Select “Potato Gratin” programme on the combi steamer and start preheat.
2. Step: Whisk together the cream, cinnamon, nutmeg, salt and pepper until smooth.
3. Step: In a 65 mm tray, arrange an even layer of sweet potatoes and turnips. 
              Drizzle with a ¼ cup of the cream, sprinkle with ½ cup of roasted mushrooms.
              Repeat process to make 8 to 10 layers. Press down on the layers to totally submerge the sweet potatoes and turnips in the cream mixture.
              Sprinkle Parmesan evenly on top layer. 
4. Step: Bake gratin in the combi steamer, at programme end remove the gratin and let it rest for at least 10 minutes before serving.