Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish and set aside.
Peel the russet potatoes and slice them into evenly-sized cubes. Rinse thoroughly under cold water, then transfer them to a large pot. Fill the pot with water, ensuring the potatoes are fully submerged, and add a generous pinch of salt. Bring to a boil and cook for 10-15 minutes or until the potatoes are tender enough to be easily pierced with a fork.
Drain the potatoes and return them to the pot. Over low heat, cook for an additional 3 minutes to allow any remaining moisture to evaporate, stirring occasionally.
Transfer the steamed potatoes to a large bowl or the bowl of a stand mixer. Beat on low speed to break up the potatoes. Pour in the melted butter (reserving 2 tablespoons for later), and season with salt and pepper. Add the cream cheese, continuing to beat, and gradually incorporate the warmed half and half until the potatoes reach your preferred level of creaminess.
Adjust seasoning with additional salt if needed. Spread the mashed potatoes evenly into the prepared baking dish. Dot the top with the reserved butter cubes.
Bake for 45 minutes, or until the top is golden and slightly crisp. Garnish with chives if desired, and serve hot.