Preheat oven to 350 degrees and roll out pie crusts into pie pans.
Prepare cake mix according to instructions on back (Duncan Hines calls for 3 eggs, 1-1/4 cup water, and 1/3 cup oil). Mix well and pour into 2 refrigerated pie crusts in pans.
Bake for 30-35 minutes or until crusts are golden brown and toothpick inserted in center comes out clean. If crusts begin to brown before pie is done, cover loosely with aluminum foil.
In medium saucepan, combine butter, 10 ounces of chocolate chips (reserve some for garnish) and sweetened condensed milk. Stir (medium heat) until smooth and pour over pies.
Garnish with extra chocolate chips!
Let cool and enjoy!