In a pan over medium heat, melt 1 tbsp (15 mL) butter; add chicken liver and shallot. Cook for 10 minutes, stirring so the liver cooks evenly. When liver is cooked, deglaze the pan with cognac (or brandy) and let reduce by half.
Meanwhile, dice butter into cubes.
Place liver mixture in a food processor and slowly add cubed butter; season with salt and pepper to taste. Pass the mixture through a fine chinois or sieve to ensure a smooth paste.
Place paste into a terrine; let set over night. Serve with fresh bread or crackers. Makes 6 to 8 servings.