Preheat oven to 350°F. Get a 13" x 9" pan, grease or spray with cooking spray. Set aside.
In large mixing bowl, combine cake mix, eggs and oil. Using a spoon, mix well until thick dough forms. Take 2/3 of dough and press into greased/sprayed pan. Press with your hands or spatula to evenly distribute. Set aside the remaining dough.
In microwave safe bowl, place cubed butter, chocolate chips and sweetened condensed milk. Heat in microwave on 50% power until melted; it took mine about 45 sec to melt. Using a spoon, stir until mixture blends and is smooth.
Pour melted mixture over the crust in pan, making sure it goes into the corners well. It will be runny but thick.
I added this step: Sprinkle 1/2 cup chopped pecans over the chocolate layer.
Take remaining dough and tear into little pieces and drop all over mixture in pan.
Bake at 350°F for 20-25 minutes, or until bits of dough are light golden and center seems set (it will still jiggle just a little).
Remove from oven and cool pan on wire rack. Cut when completely cool.
Cut into 24 squares (6 long by 4 wide). Enjoy! These are really rich!