Preheat oven to 350F degrees. Spray 9x13-inch baking dish with nonstick cooking spray (I like the kind that has flour in it).
In a medium bowl, combine cake mix, eggs and melted butter until combined. Batter will be very thick.
Stir in chips and walnuts
Spread mixture evenly into pan.
Bake for about 20-25 minutes, until golden brown and inserted toothpick comes out clean. Baking time will vary so be sure not to over bake.
Allow to cool before cutting into squares.
In a small bowl, using a whisk, combine sweetened condensed milk with melted butter and maple syrup. Stir well.
If you want to serve this sauce warm, just pop bowl into microwave and nuke it for a few seconds until warm.
