Butter Lettuce with Goat Cheese Green Goddess Dressing Recipe

1 5-ounce package soft fresh goat cheese
2/3 cup sour cream
2 cups buttermilk
2 medium avocados
2 tablespoons chopped fresh tarragon
2 tablespoons chopped fresh parsley
2 tablespoons chopped fresh chives
8 large heads of butter lettuce, quartered lengthwise (leaving some core attached)

Using rubber spatula, mix goat cheese and sour cream in medium bowl. Puree buttermilk, avocados, tarragon, parsley, and chives in blender until smooth. Gradually whisk buttermilk mixture into goat cheese mixture until smooth. Season to taste with salt and pepper. (Dressing can be made 2 days ahead. Cover and refrigerate.) Divide lettuce among plates. Drizzle with dressing.