2 sticks (1/2 pound) unsalted butter, softened
1/2 cup grated Parmesan, plus more for garnish
1/2 cup finely chopped mixed herbs, such as parsley, chives, and thyme
Kosher salt and freshly ground black pepper
4 pounds creamer potatoes
8 ears corn
4 pounds kielbasa, cut into pieces
8 dozen hard-shell clams, such as cherrystone or littleneck