Step 1 Preheat oven to 180 degrees. Place whole potatoes in a medium pot of cold salted water and bring to a boil. Simmer for 15 minutes until parboiled, but not soft, you should be able to stick a knife into the potato with a little resistance. Drain potatoes and set aside to cool. Step 2 Finely dice the onion and garlic, then grate mushrooms, including the stems, on the coarse side of a box grater. Pick the thyme leaves and set aside. Step 3 In a medium casserole pot or saucepan, heat olive oil over medium heat. Add diced onions with a pinch of salt and sautée for about 5 minutes or until translucent. Add minced garlic, thyme, tomato paste, salt and pepper and cook for 2-3 minutes, until fragrant and the tomato paste starts to thicken. Step 4 Turn heat up to medium-high. Add the mince meat to the pot and sauté until nicely browned, around 3-4 minutes. Step 5 Add half of the mushrooms and cook, stirring often until mushrooms have softened and any liquid has evaporated, around 4-5 minutes. Add the remaining mushrooms and repeat. The mixture should look glossy and rich. Step 6 Drain and rinse the can of lentils. Add to the pot, along with the Worcestershire sauce and stock. Reduce heat to medium-low and simmer for 10 minutes or until the sauce has slightly reduced. Taste, adding more salt and pepper if needed. Transfer bolognese to a baking dish roughly 30cm x 20cm and spread into an even layer. Step 7 Once potatoes are cool enough to handle, slice into thin rounds or half moons, about ½ cm thick. Layer the potato slices on top of the bolognaise, and season with salt and pepper. Add another layer of sliced potato rounds. Brush milk over the potato, top with grated parmesan and a sprinkle of salt and fresh cracked pepper. Step 8 Bake in oven for 15 minutes or until golden brown. When cooked, remove from oven and let sit for 5 minutes before serving.
