Cut cake into 1-inch cubes.
Place half the cake cubes in 13 x 9-inch cake pan.
Combine pudding mix and milk;beat until smooth and slightly thickened.
Blend in sour cream.
Pour half the pudding mixture over cake cubes; spoon half the pie filling over pudding mixture.
Repeat layers; smooth top with spatula.
Refrigerate for several hours or overnight before serving.