Prepare the Potatoes

1. Boil the Potatoes: Place the peeled and chopped potatoes in a large pot. Cover with cold water and add a pinch of salt. Bring to a boil over medium-high heat, then reduce to a simmer. Cook for 15-20 minutes, or until the potatoes are fork-tender.
2. Drain and Mash: Drain the cooked potatoes and return them to the pot. Mash until smooth and lump-free.

Mix in the Creamy Ingredients

1. Add the Cream and Butter: Stir in the heavy cream and melted butter until well combined.
2. Fold in Sour Cream and Cheese: Add the sour cream and optional shredded cheddar cheese. Mix until creamy. Season with salt and pepper to taste.

Bake the Mashed Potatoes

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Transfer to Baking Dish: Spread the mashed potatoes evenly in a greased 9×13-inch baking dish.
3. Add the Toppings: Sprinkle grated Parmesan cheese over the top and dot with pieces of butter.
4. Bake: Bake in the preheated oven for 30-40 minutes, or until the top is golden brown and the edges are bubbling.
5. Garnish and Serve: Let the potatoes rest for a few minutes before serving. Garnish with fresh chives if desired.