Heat the olive oil in a large, heavy skillet over medium-high heat. When the oil is very hot, add the livers and sear until browned on one side, about 1 minute.

Turn the livers over, add the shallots to the pan, and continue to cook until the livers are browned on the other side, about 1 minute more.

Add the thyme and cook, stirring, for another minute or so.

Remove the pan from the heat and add 2 tablespoons of the butter and ¼ cup of the cognac.

Stir to deglaze the pan, scraping up any browned bits from the bottom of the pan.

Transfer the mixture to a food processor and let cool to room temperature.

When livers are at room temperature, add the 4 tablespoons of butter and the remaining 1/4 cup of cognac and process in the food processor until smooth.

Transfer the puree to 4 4-ounce ramekins or a terrine large enough to hold it all.

Put the 3 tablespoons of butter in a bowl and microwave 30 to 45 seconds, until melted.

Add the cognac and salt and stir to combine.

Pour the butter in an even layer over the pate (dividing evenly if using ramekins).

Cover and refrigerate until ready to use (it will keep well in the refrigerator and can be frozen, as well).

Bring to room temperature before serving.