Heat oven to 350 degrees F. Coat a 2-quart baking dish with nonstick cooking spray.
Place potatoes in a large pot. Add enough water to cover. Lightly salt and bring to a boil. Lower heat; simmer for 15 to 20 minutes or until fork-tender. Drain.
In large bowl, mash potatoes with hand mixer. Add margarine, half-and-half, cream cheese with chives, garlic salt and nutmeg. Beat potatoes on medium-high speed until very smooth. Spoon into prepared dish.
Bake at 350 degrees F for 30 minutes. Sprinkle with sliced almonds; bake 15 minutes more, until lightly browned. Let stand 15 minutes before serving. Makes 12 servings.