First, add the porcini mushrooms to a mug and cover with a few tbsp of boiling water, until just covered. Set aside.
Take a large pan (ideally a large ovenproof pan as then you can bake the pasta in this dish too) over medium heat and add the cubed pancetta along with a drizzle of olive oil. You want to gently fry this to render out the fat as this adds flavour to the rest of the dish so nicely.
Whilst this is frying, peel 1 large onion of its skin, peel 2 carrots and then add to a food processor with 2 sticks of celery too. Blitz to a fine chop. You can also chop by hand.
Once the pancetta is crispy, remove it from the pan but leave behind the fat. Then add the beef mince to the pan, turn the heat to medium-high, and start breaking it apart with your spoon. Once the beef starts collecting liquid, drain this away and keep frying. This helps it turn golden brown and fry nicely rather than stew.
Once the beef has some colour, around 10 minutes, remove the soaked mushrooms from the liquid, chop them up and then add to the pan along with the mushroom liquid. Scrape up any bits at the bottom of the pan.
Add the blitzed mirepoix (the onion, carrot, celery) with some salt and pepper. Stir together and fry for 5 minutes. Add 2 tbsp tomato puree and stir together, frying for a few more minutes.
Heat the oven to 200c fan/220c regular.
Then add the tomato sauce, then fill half the jar/tin up with water and add to the pan. Nestle in a parmesan rind if you have one. Season really well with salt and pepper, let it simmer together for another 10 minutes, until the liquid has reduced down. If spitting too aggressively, turn down to medium. Taste it and adjust it as you need; it may need more salt!
At this point, get your pasta on to boil in well-salted water for a few minutes less than the package instructions.
Whilst the pasta is boiling, tip the mascarpone into a bowl and then loosen it with some pasta cooking water - a few tbsp. Add the zest of a lemon, salt and pepper. Stir together.
Once the pasta is cooked, tip it into the bolognese along with half of the mascarpone mixture. Stir together until creamy and delicious. Smooth into a layer and then with the rest of the mascarpone, dollop it in and around the pasta. Scatter over torn mozzarella and grate over lots of parmesan. Place in the oven for 15-20 minutes until the top is golden and crisp.
The video below will help with this recipe.