Scalloped Yukon Gold and Sweet Potato Gratin with Fresh Herbs

Name: Scalloped Yukon Gold and Sweet Potato Gratin with Fresh Herbs
Ingredients: 1 1/2 pounds medium Yukon Gold potatoes; 1 1/2 pounds medium red-skinned sweet potatoes (yams); 2 cups heavy whipping cream; 1 /4 cup (1/2 stick) butter; 2 garlic cloves, minced; 1 tablespoon minced fresh Italian parsley; 1 tablespoon minced fresh rosemary; 1 tablespoon minced fresh sage; 1 tablespoon minced fresh thyme; 1 1/2 teaspoons fine sea salt; 3 /4 teaspoon freshly ground black pepper; 1 1/4 cups (packed) coarsely grated Gruyère cheese (about 5 ounces)