### Ingredients:
– 4 large russet potatoes, thinly sliced
– 2 cups heavy cream
– 1 ½ cups sharp cheddar cheese, shredded
– 1 cup Gruyère cheese, shredded
– 3 cloves garlic, minced
– 2 tablespoons butter
– 1 tablespoon all-purpose flour
– 1 teaspoon salt
– ½ teaspoon black pepper
– ½ teaspoon nutmeg
– ¼ cup Parmesan cheese, grated (for topping)
– Fresh parsley, chopped (optional garnish)
### Directions:
1. **Preheat the Oven:** Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish with butter.
2. **Prepare the Potatoes:** Thinly slice the potatoes into even rounds, about ⅛ inch thick, and set them aside.
3. **Make the Cheese Sauce:** In a medium saucepan, melt the butter over medium heat. Add the minced garlic and cook for 1 minute until fragrant. Stir in the flour and cook for another minute to form a roux. Gradually whisk in the heavy cream, salt, pepper, and nutmeg. Cook, stirring frequently, until the sauce thickens, about 3-5 minutes.
4. **Add the Cheese:** Remove the saucepan from heat and stir in the sharp cheddar and Gruyère cheese until melted and smooth.
5. **Assemble the Dish:** Layer half of the sliced potatoes in the prepared baking dish. Pour half of the cheese sauce over the potatoes. Repeat with the remaining potatoes and cheese sauce, ensuring all potatoes are covered.
6. **Top with Parmesan:** Sprinkle the grated Parmesan cheese evenly over the top.
7. **Bake:** Cover the dish with foil and bake in the preheated oven for 45 minutes. Remove the foil and bake for an additional 15 minutes, or until the top is golden brown and bubbly.
8. **Garnish and Serve:** Let the potatoes cool for 10 minutes before serving. Garnish with freshly chopped parsley, if desired.
**Prep Time:** 15 minutes | **Cooking Time:** 1 hour | **Total Time:** 1 hour 15 minutes