Gather all your ingredients in one place to stay organized.
Line a baking sheet with parchment paper to prevent sticking.
Melt the semi-sweet chocolate chips in a microwave-safe bowl in 30-second intervals, stirring until smooth.
Crush the Oreo cookies in a zip-top bag using a rolling pin or your hands.
Melt the white chocolate chips in another bowl and stir in the peppermint extract.
Pour the melted semi-sweet chocolate onto the prepared baking sheet and spread it evenly.
Pour the white chocolate over the semi-sweet layer and swirl the two chocolates together.
Sprinkle the crushed Oreo cookies and optional peppermint candies on top, pressing them down slightly.
Chill in the refrigerator for at least 1 hour or until set, then break into pieces.