Soak the porcini mushrooms in 200ml (7fl.oz) water for 30 mins. Drain and reserve the soaking liquid.
Melt 25g (1oz) of the butter in a large frying pan and fry the onion with half the rosemary, the soaked mushrooms and the garlic until very soft and golden brown - this will take a good 10 mins. Remove from the pan with a slotted spoon and set aside. Discard the rosemary sprigs.
Drain the livers. Add a further 25g (1oz) of the butter to the pan, increase the heat and fry the livers briskly with the bacon until deep golden on the outside and still pink in the centre - this should take no longer than 3-4 mins. Stir in 1 tbsp of the conserve, the brandy and the onion mixture. Remove the pan from the heat and leave to cool.
Liquidise the liver mixture with the remaining butter to a smooth paste and spoon into an earthenware dish. Cover with cling film and chill for 30 mins.
Meanwhile, put the reserved mushroom liquid into a small saucepan. Cut the gelatine into small pieces and drop into the pan. Leave to soak for 10 mins. Warm over a low heat until the gelatine dissolves, then stir in the remaining conserve.
Spoon this mixture over the chilled pâté and top with the remaining rosemary sprigs and peppercorns. Chill for a further 1hr.
The pâté will keep in the fridge for up to 1 week.
It can be made ahead of time and frozen. Add the jelly up to 1 week before needed.
This pâté is particularly delicious with thin slices of toasted brioche.
For a special occasion, take the time to push the liquidised liver mixture through a mesh sieve using a rubber spatula. It is time-consuming and adds to the washing up but produces a wonderful velvety rich texture.