Heat olive oil in a large lidded pan and fry chopped onion and carrot for five minutes.
Add minced beef to the pan and fry until browned.
Stir in tomatoes, tomato purée, beef stock, bay leaf, and thyme.
Simmer the mixture for 30 minutes and season with salt and pepper.
Boil quartered potatoes in salted water for 10 to 15 minutes until tender.
Drain the potatoes and mash them thoroughly.
Mix in cream, butter, and seasoning, then preheat the oven to 190°C.
Add ketchup and Worcestershire sauce to the meat, reducing liquid if necessary.
Fry chopped leeks in butter in a separate pan until softened.
Transfer meat to an ovenproof dish and layer the leeks on top.
Spread mash over the top and bake for 30 minutes until golden.