Rinse the cut potatoes thoroughly under running water to remove any dirt or residue.
Peel and cut the potatoes into roughly equal-sized chunks or cubes, about 1 to 2 inches each, to ensure even cooking.
Fill a large pot with water and bring it to a boil. Add a pinch of salt to the boiling water.
Add the peeled and cut potatoes to the boiling water. Boil for about 15-20 minutes, or until the potatoes are fork-tender.
Once cooked, drain the potatoes using a colander. Allow them to sit for at least 5 minutes to let excess moisture evaporate, which helps in achieving a creamier texture.
While the potatoes are boiling, heat a skillet over medium heat and add 1 tablespoon of butter.
Add 1 diced sweet onion to the skillet and sauté until translucent, about 5 minutes.
Stir in 2 minced garlic cloves and cook for an additional 2-3 minutes until fragrant.
Remove the sautéed onions and garlic from the skillet and set aside to incorporate into the mashed potatoes later.
In a large mixing bowl, add the boiled potatoes. Using a stand mixer or hand mixer, begin to whip the potatoes.
Gradually add 1/3 cup sour cream, 1/4 cup whole milk, and 4 tablespoons of softened butter to the potatoes. Continue to whip until the mixture becomes smooth and creamy.
Add 4 ounces of softened cream cheese and 1/3 cup grated Parmesan cheese to the mixture. Beat until fully incorporated and the potatoes are fluffy.
Mix in 1 tablespoon of chicken bouillon seasoning, 1 teaspoon of black pepper, and the sautéed onions and garlic (if using). Whip for an additional 2 minutes to ensure all ingredients are well combined and the potatoes are light and fluffy.
Top the whipped mashed potatoes with the remaining 2 tablespoons of butter for extra richness.
Sprinkle chopped chives over the top for a fresh, vibrant touch (optional).
Transfer the whipped mashed potatoes to a serving bowl and enjoy them warm as a perfect side dish to your favorite main courses.