Gratin can be cooked up to two hours ahead. Stand, covered at room temperature. To reheat, cover with foil and place in a moderately slow oven (160C) for about 30 minutes, or until hot in centre. Delicious served with roast chicken, beef or lamb.
¼ cup dried packaged breadcrumbs
2 x 600g sweet potatoes, peeled, very thinly sliced
450g fennel bulb, trimmed, very thinly sliced
300ml carton pure cream
1 tablespoon Dijon mustard
1 tablespoon finely chopped fresh rosemary leaves
2 cloves garlic, crushed
1 chicken stock cube (10g), crumbled
1 cup shredded parmesan
Lightly grease a large ovenproof dish (12-cup capacity). Sprinkle breadcrumbs over the base.
Arrange one-quarter of the potatoes, in an even layer, over breadcrumbs. Top evenly with one-third of the fennel. Repeat layering with remaining potato and fennel, finishing with a potato layer.
Whisk cream, mustard, rosemary, garlic, stock cube and ½ cup parmesan in a large jug. Season with salt and pepper.
Pour evenly over vegetables in dish. Cover with greased foil. Place on a oven tray.
Cook in a moderate oven (180C) for 1 hour and 30 minutes. Remove foil. Sprinkle with remaining parmesan. Cook, uncovered, for a further 20 to 25 minutes, or until golden and vegetables are tender. Remove from oven.
Stand for 10 minutes before serving.