PREHEAT oven to 350°F. Reserve 10 of the pecan halves for garnish; finely chop remaining pecans.
BEAT cream cheese, sugar, eggs, sour cream, rum extract and 1/2 tsp. of the nutmeg in medium bowl with electric mixer until creamy; stir in chopped pecans. Spread into prepared crust.
BAKE 40 to 45 minutes or until filling is set. Cool completely. Refrigerate several hours or until chilled. Top with the whipped topping and reserved pecan halves just before serving. Sprinkle with the remaining 1/4 tsp. nutmeg.