Cheesy Ranch Potato Gratin

Name: Cheesy Ranch Potato Gratin
Ingredients: 2 tablespoons unsalted butter; 4 pounds large russet potatoes; 6 ounces dill havarti cheese; 2 ounces Parmesan cheese; 4 cloves garlic; 1 medium lemon; 2 tablespoons finely chopped fresh chives; 2 tablespoons finely chopped fresh dill; 1 tablespoon finely chopped fresh parsley leaves; 2 cups heavy cream; 1 cup sour cream; 2 1/2 teaspoons kosher salt; 1/2 teaspoon freshly ground black pepper