Place lentils in a saucepan with cold water to cover. Cook over a high heat until boiling, then boil for 10 minutes.
In another frying pan brown the beef mince. Once browned add the onion, celery, carrot and the garlic. Cook over low heat for 5 minutes and stir in tomatoes.
Drain lentils and reserve 300ml (1 ¼ cups) of the cooking liquid. If not enough cooking liquid top up with hot water.
Add lentils to meat mixture, then dissolve the vegemite in the cooking liquid and stir into meat mixture.
Add bay leaf and bring mixture back to the boil, lower heat and simmer for 20 minutes.
Meanwhile make the topping.
Place potato and parsnip in a saucepan and cover with water (lightly salted if you desire).
Bring to the boil and cook for about 15 minutes or until tender.
Drain into a bowl and mash together with the yoghurt and the chives.
Preheat the grill (Broiler).
Remove bay leaf from meat mixture and divide the mixture among 4 2 cup capacity ramekins.
Spoon or pipe the potato/parsnip mash over the top and sprinkle with parmesan cheese.
Place under the griller for a few minutes or until the potato topping is nicely golden.