Place the porcini in a small bowl and cover with boiling water. Peel the onions, 2 cloves of garlic and the carrots, trim the celery and pick the rosemary leaves, then roughly chop. Place a large casserole pan on a medium-low heat with 1 tablespoon of oil. Add the chopped vegetables, chilli flakes and bay, and cook for 15 minutes, or until golden and soft, stirring regularly. Remove the porcini from their soaking juices, finely chop and add to the pan. Strain in the porcini soaking liquor. Add the wine, then turn up the heat and let it bubble away for a minute or two. Add the lentils (juice and all) and tomatoes, along with 1 tin's worth of cold water. Bring to the boil, then reduce the heat to low and simmer for 1 hour or until thick and delicious. To make the pasta, pile the flour into a large bowl, make a well in the middle and gradually add 200ml of tepid water, mixing with a fork. When it becomes too hard to mix, get in there with your hands and bring it together into a ball of dough. Knead on a flour-dusted surface for 5 minutes or until smooth, then cover with clingfilm and leave to rest until you’re ready to roll it out. To make the white sauce, heat a large, deep frying pan over a medium heat with 4 tablespoons of oil. Add the flour and stir well to coat, then gradually add the almond milk, stirring continuously. Leave to bubble away for 5 minutes or until thickened. Meanwhile, place a large non-stick frying pan on a high heat. Tear in the mushrooms and dry-fry for 3 to 5 minutes, or until charred and nutty. Peel and finely slice the remaining garlic. Add 1 tablespoon of olive oil to the mushroom pan, followed by the garlic. Strip in the thyme leaves and cook for a further 2 minutes, them remove from the heat. Place a third of the cooked mushrooms into a liquidiser with the white sauce and blitz until smooth. Have a taste and season to perfection. Cut your pasta dough into 6 pieces. One at a time, flatten each piece of dough by hand and roll it out to 2mm thick using a pasta machine (or a rolling pin), keeping the pieces long. Place on a flour-dusted surface. Preheat the oven to 180°C/350°F/gas 4. Whiz the sourdough in a food processor to coarse breadcrumbs. To assemble, line a 30cm ovenproof frying pan with a large piece of oiled baking paper. Line the base with pasta sheets until completely covered, leaving an overhang around the edge of the pan. Trim the remaining pasta sheets for your layers. Layer up the lentil sauce, followed by the white sauce, a scattering of mushrooms and a couple of pasta sheets. Repeat until all the elements are used up, saving your final layer of white sauce and mushrooms for the topping. Bring up the overhanging pasta and let it fall over the filling until completely covered. Add the remaining sauce and mushrooms, then sprinkle over the breadcrumbs, grate over the cheese and pick over the sage leaves. Drizzle with a little extra virgin olive oil. Bake in the bottom of the oven for 50 minute to 1 hour until golden and bubbling. Leave to stand for 15 to 20 minutes, then tuck in! Delicious served with a simple salad.