Preheat the oven to 190℃
First you will need to get the ragu started. Heat a little bit of oil in a large saucepan, fry the onion, carrots and celery on a medium heat for about 10 minutes until they are soft. Add the rosemary and garlic then fry for a further two minutes.
Whilst the vegetables are cooking, fry the minced beef and pork in a separate large frying pan on a high heat. Cook until all the juices have evaporated, and then for a few minutes further to colour the meat.
Add the red wine to the browned minced meat and reduce by half. Add the minced beef, pork and red wine to the saucepan with the vegetables.
Pour in the beef stock, as well as the tinned chopped tomatoes.
Add the bay leaves and stir. Cook on a low-medium heat for at least 2 hours but up to 4 hours.
Place the diced butternut squash into a roasting tray with a splash of oil, season and roast for 30 minutes. Once done, take out and leave to cool.
Meanwhile, you can get the béchemel sauce ready. Warm the milk in a saucepan.
In another saucepan, melt the butter over a medium heat and then add the flour. Beat well and cook for two minutes.
Add a ladle of milk to the mixture, and beat with a whisk. Then add another ladle, and beat again until smooth. Continue until all the milk has been used up.
Add the grated cheese and stir until melted. Then add the ground nutmeg. Mix well and take off the heat. To stop the sauce forming a skin on top, you can cover it with baking paper.
If you are using dried pasta, blanche your pasta sheets in boiling salted water for a few minutes. If using fresh pasta, you don't need to do this.
To prepare the lasagne, spoon some of the ragu onto the bottom of a large roasting tray. Then spoon over a few dollops of béchemel, followed by a third of the roasted butternut squash. Then layer pasta sheets over the top and repeat for three layers of pasta.
On the fourth layer of pasta, pour only the remaining béchemel sauce over the top, covering the entire lasagne.
Sprinkle with the grated cheddar and then the grated parmesan then cook in the oven for 40 minutes or until golden brown on top.
Take out of the oven and leave to sit for a few minutes before serving.