Place peeled and cut potatoes in a large pot. Cover with cold water by 1 inch and add generous salt. Bring to boil over high heat, then reduce to medium-high and cook until fork-tender, about 15-18 minutes.

While potatoes cook, melt 3/4 cup butter in small saucepan over low heat. Add minced garlic and sauté 2 minutes until fragrant. Stir in warm milk and heavy cream, keep warm.

Drain potatoes thoroughly in colander. Return to hot pot and let sit 1 minute over residual heat to evaporate excess moisture.

Add softened cream cheese and sour cream to potatoes. Mash with potato masher or ricer until smooth and well combined.

Pour warm butter-garlic-cream mixture over potatoes. Fold in gently until fully incorporated and creamy.

Season with salt and pepper to taste. Add remaining 1/4 cup butter in cubes, folding until melted and glossy.

Transfer to serving dish. Garnish with fresh chives and parsley. Serve immediately while hot.