Place the sprouts in a large saucepan of boiling water over a high heat and boil for 3-4 minutes until nearly tender. Drain and plunge into cold water to refresh, then drain again.
Meanwhile, melt 45g (1½oz) of the butter in a large frying pan over a medium heat. Add the pancetta and cook for 2-3 minutes. Add the lemon zest, breadcrumbs and parsley and cook for 2 minutes until the breadcrumbs are toasted and golden. Season well. Remove from the pan and set aside.
To serve, melt the remaining butter in a large frying pan over a medium heat. Reduce the heat to low and return the sprouts in the pan to heat through. Transfer to a bowl and scatter with the pancetta breadcrumb mixture.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.