Luscious Four Layer Pumpkin Cake

2 layer size yellow cake mix
15oz pumpkin, divided
1/2 cup milk
1/3 cup oil
4 large eggs
1 1/2 teaspoon pumpkin pie spice, divided
8 oz cream cheese, softened
1 cup powdered sugar
8 oz cool whip, thawed
1/4 cup caramel topping
1/4 cup chopped pecans

Preheat oven to 350*. Grease and flour 2 9" round cake pans. Beat cake mix, 1 cup of the pumpkin, the milk, oil, eggs and 1 teaspoon of the pumpkin pie spice in large bowl with mixer on medium until well blended. Pour evenly into prepared pans.
Bake 28-30 minutes or until wooden toothpick inserted in centers comes out clean. Cool in pans 10 minutes. Remove from pans to wire racks; cool completely.
Beat cream cheese in small bowl with mixer on medium until creamy. Add sugar, remaining pumpkin and remaining 1/2 teaspoon pumpkin pie spice; mix well. Stir in cool whip.
Cut each cake layer horizontally in half with serrated knife. Stack layers on serving plate, spreading the cream cheese filling between layers. (Do not frost top of cake.) Drizzle cake with caramel topping just before serving; sprinkle with pecans. Store leftover cake in refrigerator.