1. Peel and finely chop the onions. Peel and thinly slice 2 garlic cloves. Pour 1 tbsp oil into a large pan and warm over a medium-low heat. Slide the onions and garlic into the pan and season with a good pinch of salt and pepper. Cook the onions for 10 mins, stirring occasionally, till the onions have started to soften.
2. While the onions cook, roughly chop both types of mushrooms and tip them into a food processor. Pulse the food processor till the mushrooms are very finely chopped. When the onions are soft, scrape in the chopped mushrooms. Cook for a further 15 mins, stirring often, till the mushrooms are tender. No food processor? Just finely chop the mushrooms by hand. Fill and boil your kettle.
3. When the onions and mushrooms are ready, add the dried red lentils and 300ml boiling water. Spoon in 1 tbsp miso and crumble in the vegetable stock cube. Stir well and bring to the boil. Pop on a lid. Simmer for a further 20 mins, stirring occasionally, till the lentils are tender.
4. Meanwhile, peel and thinly slice the remaining garlic cloves. Melt the vegan gold butter into a medium pan over a gentle heat. Slide the garlic into the pan and cook and stir for 3-4 mins till aromatic. Stir in 2 tbsp flour to form a thick paste. Cook for 1 min, stirring frequently. Slowly pour in the soya cream, continuing to stir as you add it, till the sauce is smooth and thick. Snip in the wild garlic leaves. Squeeze in a little lemon juice stir well. Remove from the heat, taste and add more salt, pepper or lemon juice if you think it needs it. Set to one side.
5. Fill your kettle and boil it again. Tip the spinach leaves into a large heatproof bowl or pan. Pour the hot water onto the spinach and stir well. Leave the spinach for 2-3 mins, till the leaves are wilted, then drain through a sieve. Use a wooden spoon to squeeze any excess water from the spinach.
6. Heat your oven to 200°C/Fan 180°C/Gas 6. Spoon roughly one-third of the mushroom sauce into a large ovenproof dish or casserole. Add some of the spinach on top, and spoon over roughly one-third of the white sauce. Cover with a layer of lasagne sheets, then repeat each step twice more, till everything is used up. Sprinkle the top of the lasagne with freshly ground pepper, and drizzle with 1 tbsp olive oil. Slide the lasagne into the oven for 40 mins, till lightly golden on top.
7. While the lasagne cooks, pick the sage leaves and pop them into a bowl. Pour 1 tsp oil into the bowl and toss till the sage is coated. When the lasagne has cooked for 40 mins, scatter the sage leaves over the top. Return the lasagne to the oven for a further 5 mins, till the sage leaves are crisp. Divide the lasagne between plates, and serve with your favourite salad on the side.
8. Get Ahead
You can make the lasagne the day before, and keep it in your fridge, ready to bake. Take it out of the fridge 30 mins-1 hr before baking to let it come to room temperature.
9. Eat Me, Keep Me
The lasgane will keep well in the fridge for up to 3 days. Reheat in the oven, covered with a layer of foil, or in the miscrowave till piping hot all the way through.