Cut the leek in half lengthways then slice each half thinly. Rinse in cold water to remove any dirt and drain well. Put into a large saucepan
Peel and crush the garlic and add to the pan
Dice the courgette and pepper (stalks and seeds removed and discarded) and add to the pan with a drizzle of olive oil
Cook over a medium heat for a minute or so till the leek starts to just soften then add the lentils, passata, vegetable stock, sugar, umami paste and tomato puree
Stir everything well together, then bubble over a low heat for 40 minutes, stirring occasionally
Thickly slice the mushrooms then add to the pan and cook for a further 5 minutes, stirring a couple of time
Preheat your oven to 180 Fan / 200 C / 400 F / Gas 6
Into a large baking dish 12 x 8.5 inches (30 x 21 cm) lay 4-5 sheets of lasagne across the bottom, overlapping slightly
Top with half of the tomato lentil sauce
Top that with another 4-5 sheets of lasagne and the rest of the tomato sauce. Lay the last 4-5 sheets of lasagne across the top
To make the white sauce melt the vegan butter in a medium saucepan over a medium heat then stir in all the flour.
Cook, stirring continuously for 1 minute then add about 1/4 of the milk. Stir until the mixture returns to a paste then stir in another 1/4 of the milk, repeating the process until all the milk is used up
Cook until it starts to bubble then turn off the heat and stir in the nutritional yeast and plenty of salt and pepper
Pour this over the top layer of lasagne sheets and spread to completely cover them
Drop in spoonfulls of pesto across the top of the white sauce then use the point of a knife or a spoon handle to swirl the two together
Add this point you can chill the lasagne and keep in the fridge for a few days
Otherwise place in the oven and bake for 35-40 minutes until golden and bubbling. If you're cooking the dish from chilled or re-heating leftovers you will probably need to cook a little longer - just ensure it's piping hot in the centre before serving!
Sprinkle with a little vegan parmesan just before serving
Recipe by The Cook & Him at https://thecookandhim.com/recipes/vegetarian-lasagne-recipe/