Prepare cake in 13×9″ pan according to box directions.
Use spoon handle to poke holes evenly across cake.
Combine sweetened condensed milk, cinnamon and nutmeg.Whisk until well blended.
Pour mixture over cake making sure it gets down into holes.
Using a knife, chop apple fie filling into smaller pieces and spread over top of cake.
Refrigerate cake for several hours.
Open frosting container and remove foil seal.
Microwave for 15 seconds and stir. Repeat this until frosting is pourable.
Pour over cake and spread with spatula to cover completely.
Refrigerate for at least several more hours.