Place potatoes in a large pot, cover with cold water, add salt, and bring to a boil

Cook until fork-tender, about 18–20 minutes

Drain potatoes well and return them to the hot pot for 1 minute to steam dry

Mash potatoes until smooth but not gluey

Gradually stir in melted butter and warm heavy cream

Add sour cream and cream cheese, mixing until fully incorporated

Stir in shredded cheese, garlic powder, and onion powder

Season with salt and black pepper to taste

Preheat oven to 375°F

Transfer potato mixture to a greased baking dish

Sprinkle extra cheese on top if using

Bake uncovered for 20–25 minutes until set and lightly golden

Let rest 5 minutes before serving