For the ragu, heat a large frying pan until hot and add the oil. Cook The Meatless Farm Co ground until browned all over at medium heat. Remove from the heat and transfer to a plate. Add the onion, celery and garlic to the pan and cook until softened. Return the ground to the pan. Add the stock and bring to the boil. Add the tomato paste and thyme, then stir well.
Stir in the tinned tomatoes. Bring to the boil again, cover and simmer for a few minutes.
For the white sauce, melt the butter in a saucepan. Add the flour and cook over the heat for one minute. Gradually whisk in the hot milk until thickened. Add the Dijon mustard, Parmesan cheese and season well with salt and pepper.
For the lasagne, put one third of the ragu sauce in the base of a 2.3 litre/4 pint shallow ovenproof dish. Spoon one third of the white sauce on top. Arrange one layer of lasagne sheets on top. Season. Spoon half of the remaining ragu on top and then half of the white sauce. Put another layer of lasagne sheets on top, then the remaining ragu and remaining white sauce. Sprinkle over the cheddar cheese.
Preheat the oven temperature to 400F.
Cook in the middle of the oven for about 45 minutes – or until golden brown on top, bubbling around the edges and the pasta is soft.