Blend the Oreos until they are very fine.
In your stand mixer cream butter the add the sugar 1/2 cup at a time until well mixed.
Add vanilla and cream and mix well ensuring the mixture is very smooth.
Add the Oreos and mix well.
If you intend to pipe the mixture make sure it's not too thick. If it is just add extra cream a little at a time until the desired consistency is reached.
If you are going to pipe the buttercream you will need to use a large tip as the Oreos can clog a smaller one.