Heat the marinated mixture until nearly all the liquid has evaporated, stirring regularly to prevent the shallots and garlic from burning. Remove from the heat and discard the thyme.
Preheat the oven to 100C/gas mark ¼. Fill a bain-marie with 5cm water and place in the oven.
Preheat a water bath to 50C.
Sprinkle the table salt over the livers and put them in a sous-vide bag. Put the eggs and the alcohol reduction in a second sous-vide bag, and the butter in a third. Seal all the bags under full pressure, then place in the water bath for 20 minutes. Remove the bags from the water bath.