Vegetarian Lasagne

First peel and very finely chop the onion and garlic. 

Toss into a large pan with the oil and salt, and bring to a medium heat for a few minutes. 

Meanwhile, thoroughly rinse your lentils under a cold tap for a few minutes, and then add to the pan. 

Pour in the wine and tomatoes, add the herbs, and give it all a good stir before turning up the heat until it comes to the boil, then turn it down again to a medium simmer. 

Finely chop the mushrooms into smithereens, almost a mince-like texture. 

When chopped as fine as you can, add those to the pan too with the gravy granules and spinach and give it all a stir. 

While the lentils are cooking and absorbing all that rich, winey flavour, you can make the white sauce. 

In a small, separate pan, heat the oil, flour and mustard together and stir briskly to form a rough paste. 

Add a splash of milk to loosen it, and another, and another, stirring all the time. 

Gradually add the milk until it is all incorporated, and leave it to cook on a low heat for around 10 minutes, where it will thicken considerably. 

Now turn your oven on to 180C, and grab a suitable dish, one that looks like it will hold the same amount of lentil-mushroom-ragu that you have. 

Spread a layer of ragu into the bottom of the dish to cover it. 

Lay lasagne sheets over the top, leaving no gaps between them. 

Spread a thin layer of white sauce onto the dry pasta. 

Then repeat: ragu, pasta, sauce, until the ragu is all used up. 

Top with a final layer of pasta sheets, then a generous layer of white sauce, carefully spreading it right to the edge. 

Sprinkle breadcrumbs generously across the top, and carefully place into the centre of the oven. 

Bake for 40 minutes, until golden and crisp around the edges. 

A knife inserted into the middle should go through the pasta easily. 

If not, bake for a further 10 minutes. 

Cut into portions as desired, and serve.