To prepare the tomato sauce heat the butter in a large saucepan over a medium high heat.
Sauté the onion until it softens, about 5-7 minutes. Add the garlic, carrot and celery and sauté a further five minutes, stirring occasionally.
Add the chopped tomatoes, tomato purée and bay leaves and season well.
Reduce heat to medium low and simmer gently with the lid half on for half an hour (or longer if you have the time). Stir in the fresh chopped parsley at the end of cooking.
Meanwhile, prepare your vegetables. Quarter your peppers and cut part way so they are flat. Brush with olive oil and grill until softened (I used my Tefal Optigrill but you could do this on the hob or under a grill, or even roast them for half an hour in a hot oven). Slice the courgettes lengthwise and do the same. Set aside to cool.
Heat 2 tbsp olive oil in a large sauté pan over a high heat. Quickly cook the mushrooms and, when they are nearly ready, stir in the spinach leaves and cook until wilted. Set aside in a colander to drain.
To prepare the cheese sauce, heat the butter over a medium high heat in a small saucepan.
When the butter is hot stir in the flour and cook for one minute.
Remove from the heat and whisk in the milk. Return pan to the heat and cook, stirring constantly, until the mixture thickens.
Remove again from the heat, stir in the grated cheese and mustard. Set aside with the lid on until needed.
To assemble, place two soup ladles worth of tomato sauce onto the bottom of a 9 x 13 inch casserole dish.
Top with a layer of lasagna noodles and then the layer of drained mushroom/spinach. Season this layer well with salt and pepper.
Add another layer of noodles and a layer of tomato sauce followed by a layer of cheese sauce.
Add a layer of your grilled vegetables, more noodles, more tomato sauce and finish off with a layer of cheese sauce.
Spoon the wild garlic pesto in 1 tsp drops over the top of the cheese sauce, sprinkle with extra mature cheddar cheese and bake at 180 C/ 350 F for 30-40 minutes until golden and bubbly.
Leave to stand for ten minutes before serving with a lovely fresh side salad and crusty bread.
Regular basil pesto can be used instead of wild garlic, if it is not available.