Heat a frying pan over medium-high heat with a little oil. Soften the onion, then cook the garlic for 30 seconds. Add mince, break it up and brown thoroughly. Stir in tomato paste, Worcestershire, salt, pepper and optional paprika. Cook off excess moisture, stir in corn and taste. Set aside.

Peel and slice potatoes: 2–3 mm for the base and about 3 mm for the other layers. Rinse in cold water, drain thoroughly and pat completely dry. Toss lightly with the potato oil and salt.

Heat oven to 180°C fan. Generously butter the bottom and sides of a medium oven-safe glass baking dish. Add a complete overlapping layer of the thinner potato slices. Add a very light drizzle of oil and pinch of salt. Bake uncovered for 12–15 minutes until the edges begin to set. Do not add cooking liquid yet.

Layer potato base, a little cheese, mince, potatoes, mixed cheese, remaining mince, final potatoes, then cheese. Do not compress heavily. Use mainly cheddar or tasty cheese on top, with a little Parmesan if using.

Mix stock and cream or milk. Pour slowly around the edges. Use no more than the 0.75 cup total, and stop earlier if liquid reaches about one-quarter to one-third of the assembled bake.

Cover tightly with foil and bake at 180°C fan for 40–45 minutes. Remove foil and test the central potatoes with a knife. Bake uncovered for another 15–20 minutes until the potatoes are very tender, the cheese golden and the edge liquid reducing.

Rest for 10–15 minutes before cutting so the layers and sauce settle. Add fresh parsley after cooking if using.