In a small bowl, whisk the 1 cup heavy cream, 1/4 cup finely chopped fresh flat-leaf parsley, 1/4 cup snipped fresh chives, pinch freshly grated nutmeg, and a pinch each of sea salt and freshly ground black pepper together. Add half of the 2 1/2 ounces Gruyère or other semi-firm Swiss cheese, mix to combine.☞ TESTER TIP: If you prefer a slightly thicker sauce in your zucchini gratin, lay the zucchini slices on paper towel, sprinkle with salt, and let them rest for 15 minutes so that they release some liquid. Pat dry before proceeding with the recipe.