Cream the butter and shortening in a large mixing bowl using an electric mixer on medium speed until light and fluffy, about 2-3 minutes.
Add marshmallow fluff and mix on medium speed until well incorporated.
Gradually add powdered sugar with the mixer on low speed to prevent a sugar cloud; once added, mix on medium speed until fully combined.
Add salt and vanilla extract, mixing until well blended.
If the frosting is too thick, add heavy whipping cream, one tablespoon at a time, until the desired consistency is reached.
Gently fold in the coarsely chopped Oreos.
Frost your treats using a spatula or piping bag and enjoy!
