Remove zest for both lemons. Set aside.
Cut lemons in 1/2. Squeeze the juice from 3 of the halves into a bowl. Remove seeds, if any are in the bowl. Reserve remaining 1/2 lemon for serving salmon.
Place lemon zest, lemon juice, butter, basil, thyme and parley food processor. Blend until smooth.
Remove from processor and make a mound on a large piece of plastic wrap.
Roll plastic wrap around butter, forming butter and shape into a long roll with your hands.
Twist the ends to seal.
Place in refrigerator and chill.
Note - Leftover butter will keep for up to a week in the refrigerator and several weeks in the freezer. You will find it is delicious on steaks, burgers, vegetables (especially asparagus) and many other dishes.