These bars are absolutely a chocolate lover's delight! I have been making these for over 30 years but my recipe differs slightly. This is how I make mine: I use 24 oz. Oreos. Crush about 3/4 of Oreos and set aside the remaining 1/4 Oreos. Mix the melted butter with the crushed Oreos and press into a 9 x 13 inch pan. Melt 1-1/4 cups of regular chocolate chips with the condensed milk in the microwave, add 1 tsp. vanilla extract and pour on top of the Oreo crust. Coarsely chop the remaining Oreos, sprinkle on top with about a 1/2 cup of chocolate chips and 1/2 cup of white chocolate chips and 1/2 cup of walnuts. Bake for about 25 to 30 minutes until set. Putting the extra 1/4 cup of chocolate chips in the condensed milk filling makes the fudge mixture more solid so they cut easily and make a more solid bar cookie. You have to let these completely cool before cutting, I would suggest putting in the refrigerator for a quick chill. If not cooled all the way, they really make a mess when you cut them into bars. These are always the first on my cookie trays to be devoured and everyone asks for the recipe. Excellent recipe!
These are very rich and good! They are a little messy (the crust is crumbly) but is not a big deal. Made as is and took to share with our bowling team; all of them fought for the leftovers and the recipe! Made for March TOTM Tag 2010.