Preheat the oven to 180 °C. Roughly chop the peppers, courgette, aubergine, butternut squash and red onions into chunks. Place in a roasting tin with 2 crushed garlic cloves and drizzle with olive oil. Roast in the oven for 40 minutes or until the butternut squash is cooked through and soft.
Meanwhile, make the bechamel sauce. Melt the butter in a saucepan over a medium heat. Once melted, add the flour and mix with a wooden spoon to form a dough-like mixture. If a dough-like mixture has not formed, adjust with a little more flour. Reduce to a low heat and pour a little milk into the saucepan, whisking continuously. A smooth sauce should form which will thicken quickly. Carefully keep adding milk and whisking until the sauce reaches the correct consistency. Don’t worry if there are lumps, these should disappear as you keep whisking. Once the sauce reaches the correct consistency, season with pepper and place it to one side.
Now for the spinach and ricotta filling. Drizzle a little olive oil in a sauce pan, heat for 2 minutes over a low heat before adding 2 crushed cloves of garlic. Cook the garlic for 2 minutes, continuously stirring so it does not stick to the bottom of the pan. Add the spinach leaves and leave to wilt. Once wilted remove the pan from the heat and add ricotta, stir until the ricotta has melted.
Once the vegetables are cooked, remove from the oven. It’s now time to assemble the lasagne.
In an oven proof dish, put a layer of the bechamel sauce followed by a layer of lasagne pasta sheets. Then place another layer of bechamel sauce on top of the lasagne sheets. Then a layer of roasted vegetables and the spinach and ricotta mixture, followed by another layer of pasta sheets. Repeat until you have used up all the roasted vegetables and the spinach and ricotta mixture, I usually aim for 3 layers.
On the top layer of pasta, place the remaining bechamel sauce and sprinkle with the grated cheddar cheese. Bake in the oven for 35 minutes, or until the pasta is cooked through and the top is golden brown.