Heat over to 325°. Generously grease and flour 12-cup bundt cake pan.
In large bowl, beat cake mix, pumpkin, water, oil, pumpkin pie spice and eggs with an electric mixer on low speed until moistened, then on medium speed for 2 minutes, occasionally scraping bowl. Pour batter into pan.
Bake 40 to 45 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; remove from pan to cooking rack. Cool completely, about 1 hour.
In small microwavable bowl, microwave frosting uncovered on Low 10 to 20 seconds, stirring until thick drizzling consistently. Spoon over cake.