2 cups crushed vanilla wafers
1 cup finely chopped pecans
1 (18-ounce) package carrot or spice cake mix
1 cup canned pumpkin
2 tablespoons water
3 cups powdered sugar
4 ounces cream cheese, softened
2 teaspoons vanilla
1/2 cup caramel ice cream topping
16 pecan halves
Heat oven to 350°F. Grease and flour 3 (9-inch) round cake pans; set aside.
Combine wafer crumbs, chopped pecans and 1/2 cup butter in bowl. Beat at medium speed, scraping bowl often, until mixture resembles coarse crumbs. Press mixture evenly onto bottom of prepared pans.
Combine cake mix, pumpkin, 1/4 cup butter, eggs and water in same bowl. Beat at medium speed, scraping bowl often, until well mixed. Spread 1 1/2 cups batter over crumbs in each pan. Bake 18-23 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes; remove from pans. Cool completely.
Combine powdered sugar, 2/3 cup butter, cream cheese and vanilla in bowl. Beat at medium speed, scraping bowl often, until light and fluffy.
Place 1 cake nut-side down on serving plate. Spread cake with 1/2 cup filling mixture. Continue layering cakes with 1/2 cup filling mixture between layers. Frost sides only of cake with remaining filling. Spread caramel ice cream topping over top of cake, drizzling some over sides. Arrange pecan halves in ring on top of cake. Store refrigerated.
To remove cake easily from pan, place wire rack on top of cake and invert; repeat with remaining cakes.