Leave 1 cup unsalted butter at room temperature for 20-30 minutes until it dents easily when pressed but isn't greasy or melted.
1 cup unsalted butter
Mince 6 anchovy fillets finely with a sharp knife until nearly paste. Drain 2 tablespoons capers and pat dry with paper towels, then chop coarsely. Mince 2 garlic cloves and chop 2 tablespoons fresh parsley.
6 fillets anchovy, 2 tablespoons capers, 2 cloves garlic, 2 tablespoons fresh parsley
In a mixing bowl, combine softened butter with minced anchovies, chopped capers, minced garlic, chopped parsley, 1 teaspoon lemon zest, and ¼ teaspoon black pepper. Stir gently until evenly distributed with no large chunks.
1 cup unsalted butter, 6 fillets anchovy, 2 tablespoons capers, 2 cloves garlic, 2 tablespoons fresh parsley, 1 teaspoon lemon zest, 0.25 teaspoon black pepper
Spoon the butter mixture onto plastic wrap and shape into a log about 1½ inches in diameter. Roll tightly in plastic wrap, twisting ends to seal.
Refrigerate the wrapped butter log for at least 30 minutes until firm enough to slice cleanly but still spreadable at room temperature.