Line 8x8 inch square baking pan with foil, lightly butter.
In the bowl from standing mixer, stir together white chocolate pieces and marshmallow creme. Set aside.
In large saucepan combine butter, sugar, heavy cream, salt and vanilla.
Cook over medium heat constantly stirring until mixture begin to boil.
Boil for 4 minutes, stirring continuously. Mixture burns easily, so make sure to keep stirring.
Remove from heat and pour over chocolate marshmallow mixture.
Place bowl on mixer and beat for 1 minute until chocolate is fully melted.
Remove from mixer and by hand stir in oreo cookie pieces.
Pour into baking pan, refrigerate until set (at least 4 hours)
Cut into delicious bite sized pieces!