Lamb Pot Roast

Ingredients

• 2 (14 oz) top round lamb roasts
• 2 slices prosciutto
• 1 tbsp olive oil
• 4 None small carrots, halved crosswise and lengthwise
• 1 None medium red onion, peeled, quartered
• 1 clove garlic, quartered
• 1 stalk celery, trimmed, quartered
• 1 2/3 cups chicken stock
• 2 lb potatoes, peeled, chopped
• 1 lb celeriac, peeled, chopped
• 1 1/2 tbsp butter
• 1/4 cup heavy cream
• 1 tbsp fresh flat-leaf parsley leaves, coarsely chopped