Meanwhile, prepare the bolognese. Fry the pancetta with olive oil in a large pan over a high heat until golden. Add the diced vegetables, season with salt, then cook on a medium heat for about 5 minutes until the veg is soft and lightly golden. Add the beef mince, breaking it down as it cooks to keep it as fine as possible. Season, then add half the butter to help the beef caramelise. When the beef starts to colour, pour in the wine, let the alcohol evaporate for 30 secs, then stir in the tomato paste. After 1 min, add the passata, stock (or water) and sage, then let it simmer on a low heat for about 2h until reduced and rich. Add a splash of milk (if using), cook for 5 more mins, then check the seasoning.
