Melt the butter in a pan over medium heat. Cook the onions until golden brown, 7 to 10 minutes. Add livers, salt, pepper, garlic, bay and thyme; cook until livers are no longer pink, 3 to 5 minutes.
Flame with brandy then pour in Madeira; remove the bay and thyme. Transfer to a blender, add cream and lemon juice; process until smooth. Transfer to an oven-proof dish, cover and place in a water bath.
Bake in the preheated oven for 15 minutes. Chill in the refrigerator.
Colour and flavour will deteriorate quickly after 2 to 3 days. It freezes well but the texture does deteriorate a little but nit enough for it to be less yummy.