Preheat the oven to 350 degrees F.
Using a mandolin, thinly slice the potatoes into rounds, and then soak, rinse, and dry the potatoes. Coat the bottoms of 4 fluted (8-ounce) oval ramekins with 2 tablespoons butter and sprinkle the garlic evenly among the ramekins, and set aside.
In a medium bowl, whisk together the milk, cream, eggs, nutmeg, salt, and pepper. In the ramekins, layer the potatoes, Gruyere, and cream mixture. Press down lightly with hands to compress. Top each ramekin with tabs of butter and the Parmesan. Place the ramekins in a water bath and bake until tender and golden brown. Remove the ramekins from the water bath and let rest for 30 minutes before serving.
Professional Recipe: This recipe was provided by a chef, restaurant or culinary professional and makes a large quantity. The Food Network Kitchens chefs have not tested this recipe in the proportions indicated and therefore cannot make any representation as to the results.