To prepare this paté you need to start a day in advance.
Clean and wash the chicken livers, and pat dry with a kitchen towel.
Cut livers in four pieces each, and put into a bowl with the milk.
Let marinate in the fridgre overnight.
Remove chicken liver from the milk, and pat dry.
In a frying pan, sautè onion and garlic with half of the butter, until onion is translucent.
Add the chicken liver and the sage (and thyme if you want) , adjust salt and pepper to taste and cook for 3 minutes. Add 1 Tbs brandy and after 3 minutes more, remove from heat and let cool.
In the food porcessor, process the chicken livers with the remaining butter, last Tbs of brandy, and the lemon juice until smooth
Mix untill the paté is soft and creamy. In case It's too dense, add the beef stock untill you get the desired consistency.
Chill in the fridge for at least two hours before serving.