Line a 9x9-inch square pan with foil, sprayed lightly with nonstick cooking spray.
Break 12 Oreos into bite sized pieces.
Finely chop the other 8 Oreo cookies into crumbs.
In a large saucepan bring the sugar, butter and evaporated milk to a full rolling boil over medium heat, stirring constantly. Boil for 4 minutes or until 234 degrees Fahrenheit on your candy thermometer, stirring constantly.
Remove from heat and add vanilla, chocolate chips, crushed Oreo crumbs, and marshmallow creme. Stir until well blended and chocolate chips are melted.
Pour into prepared pan and smooth stop with spatula. Sprinkle broken Oreos on top. Use hand or spatula to push Oreos gently into fudge.
Cover and chill for at least one hour until firm.
Store in fridge in airtight container for up to 3 days.