Preheat the oven to 350°F. Lightly grease a 15 x 10-inch sheet pan with nonstick cooking spray or butter.
In a large bowl, whisk together the cake mix, pudding mix, milk, oil, eggs, and sour cream.
Fold in 1 can of the coconut pecan frosting until smooth and well combined.
Pour the batter into the prepared sheet pan and spread into an even layer.
Bake for 20 to 25 minutes, until a toothpick inserted into the center comes out with a few moist crumbs. Let cool completely.
Scoop or spoon the remaining can of coconut pecan frosting evenly over the top of the cooled cake, and spread in an even layer with an offset spatula.
Slice and serve directly from the pan. If desired, serve with whipped cream, ice cream, and toasted chopped pecans.