Combine first 6 ingredients in a medium bowl. Beat with a mixer at medium speed until well combined. Beat in black pepper and 3/4 teaspoon salt; set aside.
Heat 8 cups water and remaining 1/2 teaspoon salt in a large saucepan over high heat; bring to a boil. Add peas, cover, and cook 6 minutes or until crisp-tender. Drain and pat dry with paper towels.
Place warm peas in a large serving bowl; top with herb butter, and toss to combine. Garnish, if desired.