HEAT oven to 350°F. In large bowl, combine cake mix, water, vegetable oil and eggs; mix well. Beat on high speed 2 minutes.
STIR in mincemeat. Pour into well-greased and floured 10-inch fluted or tube pan. Bake 45 to 50 minutes or until toothpick inserted near center comes out clean. Cool 10 minutes; remove from pan. Cool completely.
COMBINE eggnog and whipped topping mix in small bowl; mix well. Beat on high speed 4 minutes or until mixture forms soft peaks. Serve topping over cake slices. Store leftover topping in refrigerator. Store leftover cake covered at room temperature.