Creating Mashed Potato au Gratin can be straightforward if you follow these simple steps:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Boil Potatoes: In a large pot, add the cubed potatoes and cover them with water. Bring to a boil and cook for about 15-20 minutes, or until tender.
3. Drain Potatoes: Once cooked, drain the potatoes and return them to the pot.
4. Mash Potatoes: Mash the potatoes until smooth.
5. Heat Cream and Milk: In a saucepan, combine the heavy cream, milk, butter, and minced garlic. Heat over medium until the butter melts and the mixture is warm.
6. Combine Ingredients: Pour the cream mixture into the mashed potatoes. Stir until well combined. Season with salt, pepper, and paprika.
7. Add Cheese: Fold in the cheddar and Gruyère cheese, mixing until the cheese is melted and incorporated.
8. Transfer to Baking Dish: Spread the mashed potato mixture into a greased 9×13-inch baking dish.
9. Top with Parmesan: Sprinkle the grated Parmesan cheese evenly over the top.
10. Bake: Place the baking dish in the preheated oven and bake for 30-35 minutes, or until the top is golden and bubbly.
11. Cool Slightly: Remove from the oven and let it cool for about 10 minutes before serving.
12. Garnish: Sprinkle with fresh parsley for a pop of color and flavor.

These steps will guide you in creating this incredible dish effortlessly.