Place a large shallow casserole pan on a medium heat with 250ml of water. Halve the aubergines lengthways and place in the pan. Peel, quarter and add the onions, then cover with a lid and cook for 20 minutes. Meanwhile, peel and finely slice the garlic, and pick the sage leaves. Preheat the oven to 200ºC/400ºF/gas 6.
Remove the lid, and once most of the liquid has cooked away, make a well in the middle. Add 3 tablespoons of oil, the garlic, chilli flakes and most of the sage leaves, then finely grate in the lemon zest. Once golden, scrunch in the tomatoes, pour in 2 tins' worth of water, and simmer for 20 minutes, stirring occasionally.
Remove the pan from the heat, grate in the cheeses, then season to absolute perfection with sea salt and black pepper. Tear in the pasta sheets and mix up really well to coat and separate, then pull some of the sheets to the top to create a top layer. Bash the almonds until fine and rub the remaining sage leaves with oil, then sprinkle on top. Use the back of a spoon to create some dips and wells, and bake for 25 minutes, or until golden and bubbling.
I love this served with a big crunchy green salad dressed with balsamic vinegar.