In a large mixing bowl, combine cake mix, sweet potatoes, eggs, water, oil, and pumpkin pie spice. Beat with an electric mixer on low speed just until combined. Beat on medium speed for 2 minutes more, scraping bowl occasionally. Stir in cranberries and finely chopped pecans. Spread batter into prepared pans.
Bake for 30 to 35 minutes or until a wooden toothpick inserted near centers comes out clean. Cool in pans on wire racks for 10 minutes. Remove cake layers from pans; cool thoroughly on wire racks.
Place one cake layer on a serving plate. Frost top of the cake with about 1/3 cup cream cheese frosting. Top with the second cake layer. Frost top and sides of cake with remaining frosting. Sprinkle with additional toasted pecans.