Line a mini muffin tin with paper liners and set aside.
Melt dark chocolate wafers in a microwave-safe bowl in 30-second increments, stirring between each, until smooth.
Stir in peppermint extract and vegetable oil until fully combined.
Spoon about 1 tablespoon of the melted chocolate into each liner.
Sprinkle crushed peppermint candies and chopped cookies on top of each.
Refrigerate for 30 minutes or until firm. Serve chilled or at room temperature.