Line a 9" baking pan with aluminum foil and grease.
In a medium saucepan combine the cake batter, butter, and sweetened condensed milk over medium-high heat.
Bring to a boil and cook for 3 minutes, stirring constantly.
Remove from heat and stir in the white chocolate, marshmallow cream and 2 cups of the crushed Oreos.
Keep stirring until everything is melted together (obviously the cookies won't be melted).
Pour the mixture into the prepared pan and cover with the remaining cookies and sprinkles - pressing gently into the fudge.
Cover and chill until firm, at least 4 hours.
Lift from the pan and cut into small bite sized pieces. Indulge
Notes
*if there are no Birthday Oreo's on the shelves of your local market, leave, they suck. If there are none on the shelves after a three store search, substitute with classic Oreo's and extra sprinkles.