Bring a Dutch oven of salted water to a boil, then add the peeled and cubed Yukon gold potatoes and cook until tender, 15-18 minutes. Visual cue: a fork should slide in easily with little resistance.

Drain the potatoes thoroughly in a colander so excess water doesn’t make the mash loose. Visual cue: shake the strainer gently for 10 seconds to remove surface steam.

Mash the hot potatoes with softened cream cheese, sour cream, 6 tablespoons of the divided butter, and warmed whole milk until smooth. Visual cue: the mash should look glossy and uniform with no visible lumps.

Season the mash with garlic powder, 1 1/2 teaspoons salt, and black pepper, stirring until evenly distributed. Visual cue: specks of black pepper should be evenly spread throughout.

Spread the mashed potatoes into a buttered 9x13-inch baking dish and dot the top with the remaining butter. Visual cue: the surface should be level and the butter dots should be visible.

Cover tightly and refrigerate up to 2 days. Visual cue: foil should be snug with no gaps to prevent drying out.

Remove from the refrigerator and let sit at room temperature for 30 minutes before baking. Visual cue: the dish should look slightly warmer and less firm at the edges.

Bake covered at 350F for 30 minutes, until hot throughout. Visual cue: steam should lift under the foil when you lift one corner.

Bake uncovered at 350F for 15-20 minutes until hot and golden on top. Visual cue: the surface should develop golden patches rather than remaining pale.

Sprinkle the top with paprika and chives, then serve immediately. Visual cue: garnish should look fresh and bright against the golden surface.