Pot Roast Lamb with Potato Celeriac Mash

Ingredients

• 2 400g lamb round or topside roasts (heart smart or trim lamb)
• 2 pieces prosciutto or thin bacon
• 1 tablespoon olive oil
• 4 small (280g) carrots, halved crossways and lengthways
• 1 medium (170g) red onion, peeled, quartered
• 1 clove garlic, peeled, quartered
• 1 stick (100g) trimmed celery, quartered
• 1 1/2 cup (375ml) chicken stock
• 800 gram potatoes, peeled, chopped
• 400 gram celeriac, peeled, chopped
• 20 gram butter
• 1/4 cup (60ml) cream or milk
• 1 tablespoon chopped, fresh flat-leaf parsley