HEAT oven to 350°F. Prepare cake batter as directed on package; stir in carrots, pineapple and 3/4 cup of the pecans. Pour into two 8-inch square baking pans. Bake 25 to 30 min. or until toothpick inserted in centres comes out clean. Cool 10 min.; remove to wire racks. Cool completely.
BEAT cream cheese and sugar with mixer until well blended. Stir in whipped topping.
STACK cakes on serving plate, spreading 1-1/2 cups of the cream cheese mixture between layers. Spread top and sides of cake with remaining cream cheese mixture. Sprinkle with remaining 1/4 cup pecans. Refrigerate leftovers.