Dump the chicken livers into a bowl, then cover with milk. Cover the bowl, and then transfer it to the fridge. Allow the livers to soak for at least 6 and up to 12 hours. Then, drain them in a colander, discarding the milk.
Preparing the pâté
Warm 2 tablespoons of butter in a large skillet over medium heat, then stir in the shallots and sage. Sauté them in the oil until fragrant, about 3 minutes. Then, add the reserved livers and pour in the water. Sprinkle with salt, and bring to a simmer over medium-high heat until tender and barely cooked through. Turn off the heat, and let the livers cool at room temperature for about 10 minutes.
Transfer the cooked livers and shallots to a food processor. Pour in the sherry. Process the livers, adding a tablespoon of butter to the feeding tube at a time, until all the butter is incorporated and the pâté is uniformly smooth.
To finish the pâté
Spoon the pâté into individual ramekins or small jars, allowing ½ inch of head space. Arrange a sage leaf over the pâté, and then pour a thin layer of ghee or clarified butter over the pâté, until completely covered. Transfer to the fridge and chill until the ghee solidifies.
Allow the pâté to come to room temperature before serving.