Cook potatoes in large pot of boiling salted water until tender, about 20 minutes. Drain potatoes and return to same pot. Add 12 ounces of cream cheese and mash well. Mix in sour cream and chopped garlic. Season potatoes to taste with salt and pepper. Transfer to 15x10x2-inch glass baking dish. Drizzle with melted butter.

Preheat oven to 375°. Bake potatoes uncovered until heated through, about 30 minutes.