Preheat the oven: preheat the oven to 180°C / 350-375°F / Gas Mark 4-5.
Cream sauce: add the dried thyme to the heavy cream and stir till consistently mixed together. The set aside.
Onion: use a knife and cutting board to peel and dice the onion.
Potatoes: use a vegetable peeler to peel each potato (discard the skins) then use a knife to thinly slice each potato.
Baking dish: grease a large 20 x 30 cm (8 x 12 inches) baking dish with olive oil.
Beef mince: place a large frying pan onto the stove top and turn the heat to high. Add the olive oil and garlic and cook for 1 minute. Next add the beef mince, salt, pepper and onion. Cook using a wooden spoon to break up any clumps of meat as you go. Add the tomato paste and Worcestershire sauce at the end and stir to combine. It will take 8-10 minutes for the beef to cook.
Layers: spread a layer of the sliced potatoes across the base of the baking dish. Top this with a layer of the cooked beef mince. Then repeat another layer of potatoes, followed by a layer of beef mince. Top the 2nd potato layer with a final layer of the potatoes.
Combine: next pour the cream sauce into the dish. Cover with tin foil then transfer to the middle shelf of the oven. Bake for 50 minutes.
Cheese topping: after 50 minutes use oven mitts to remove the potato bake from the oven and place it onto a heatproof surface. Take the aluminium foil off and discard. Sprinkle the grated cheese over the top of the dish then use the oven mitts to return the baking dish to the oven. Bake the dish for a further 10 minutes to allow the cheese to melt.
To serve: use the oven mitts to again remove the baking dish from the oven and place it onto a heatproof surface. Garnish with chopped parsley then let the dish rest for 10 minutes (sauces thickens during this time). When ready portion onto plates with steamed greens and season with black pepper.