Soak livers in milk, 500ml water, and 10g salt for one hour.
Rinse and drain the livers well.
Preheat the oven to 130°C.
Boil Madeira, port, shallots, thyme, garlic, and Cognac until reduced by one-third.
Process livers and reduced liquid in a blender, adding eggs one at a time.
Gradually blend in 400g melted butter, remaining salt, and pepper.
Line a 23cm x 9cm x 8cm terrine tin with greaseproof paper.
Sieve the mixture into the tin and cover with greaseproof paper.
Place tin in a tray filled with boiling water reaching two-thirds up the sides.
Bake under perforated foil for 40 minutes until center reaches 65°C-70°C.
Cool at room temperature for 30 minutes, then refrigerate.
Unmold the parfait by dipping the tin in hot water and lifting the paper.
Smooth surfaces with a warm palette knife and chill to firm up.
Coat all sides of the parfait with a beaten mixture of 75g butter and 75g lard.
Chill for at least one to two days before serving.
Slices thick and serve with chutney and toasted sourdough.