Melt the fat or butter in a skillet and sauté the chicken livers, in batches, until firm. Remove from the heat and let stand while peeling the eggs and cutting the onions into quarters. Reserve the melted fat or butter in the pan.
Using a meat grinder, grind the livers, eggs, and onions together. Add the reserved melted fat or butter and salt, pepper, and Cognac to taste. Mound the mixt