Then add remaining ingredients to the butter and mix well to combine (I use a fork for this).
2 tsp dijon mustard, 1 garlic clove, 2 tsp finely chopped chives, 1 cup flat leaf parsley, 1 tsp worcestershire sauce, 1 tsp lemon juice, 2 tsp finely grated parmesan cheese, ½ tsp fine salt, a few grinds of fresh black pepper