Step 1 Preheat oven to 190°C. Spray a large saucepan with olive oil and set over medium heat. Add onion; cook, stirring occasionally, for 5 minutes, or until soft. Add mushrooms and cook, stirring occasionally, for 3–4 minutes, or until browned. Add garlic and oregano; cook for 1 more minute.
Step 2 Add beef mince to pan; cook, breaking up mince with a wooden spoon, for 4–5 minutes, or until browned. Add red wine; simmer until mixture reduces by half. Add tomato paste and cook for 1 more minute. Add crushed tomatoes with ¼ cup water and simmer for 10 minutes, or until thick.
Step 3 Meanwhile, set a large chargrill pan over high heat. Spray sliced eggplant lightly with olive oil; grill for 2 minutes per side, or until tender and lightly charred.
Step 4 Bring a medium saucepan of water to the boil. Add potatoes; cook for 12–15 minutes, or until tender. Drain potatoes well; return to saucepan. Add skim milk to pan and mash until smooth. Stir grated parmesan through mash.
Step 5 Arrange beef-mince mixture and eggplant slices, in layers, in 4 x 375ml-capacity ovenproof ramekins, topping each with one-quarter of the potato mash.
Step 6 Place pies in oven and bake for 15–20 minutes, or until potato topping is golden. Serve.