Boil peeled potato chunks in salted water for 18–20 minutes until fork-tender. Starting the potatoes in cold water helps them cook evenly and prevents hard centers.
Drain the potatoes well and return them to the warm pot for 1–2 minutes so excess moisture evaporates. This creates thicker and creamier mashed potatoes.
Mash the potatoes while hot until smooth. Avoid overmixing because potatoes can quickly become sticky and gluey.
Stir in butter and softened cream cheese until fully melted. These ingredients create a silky and rich texture that blends smoothly into the potatoes.
Slowly mix in warm milk, heavy cream, garlic powder, onion powder, black pepper, and salt. Gradual mixing helps you control the consistency more easily.
Add shredded cheddar and mozzarella cheese a little at a time until melted and creamy. Freshly shredded cheese melts better and creates a smoother texture.
Garnish with chopped chives and serve hot. Keeping the potatoes warm before serving helps preserve their creamy consistency.