Crush the Oreo cookies finely using a food processor or a rolling pin.
In a mixing bowl, combine the crushed Oreos with the softened cream cheese.
Roll the mixture into small balls, about 1 inch in diameter, and place them on a baking sheet lined with parchment paper.
Chill the rolled balls in the refrigerator for at least 30 minutes to firm them up.
Melt the chocolate chips with the vegetable oil in a microwave-safe bowl in 30-second increments until smooth.
Dip each chilled truffle into the melted chocolate, covering it completely, and return it to the parchment-lined sheet.
If desired, immediately sprinkle decorations on the chocolate before it sets.
Allow the chocolate to set for about 30 minutes at room temperature or refrigerate until firm.