Beat butter and sugar at medium speed with an electric mixer until light and fluffy. Add eggs, 1 at a time, beating until blended after each addition. Add pumpkin, beating until blended.
Combine flour and next 4 ingredients. Combine buttermilk, vanilla, and ginger. Add flour mixture to butter mixture alternately with gingered buttermilk, beginning and ending with flour mixture. Beat at low speed after each addition. Fold in chopped pecans. Pour batter into 2 greased, parchment paper-lined 9" round cakepans.
Bake at 350° for 18 to 20 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 minutes; remove from pans, and cool completely on wire racks.
Spread Ginger-Cream Cheese Frosting between layers and on top and sides of cake. Cover and chill overnight.