Line the baking pan with parchment paper, leaving some overhang for easy removal later.
In a double boiler or microwave-safe bowl, melt the white chocolate over low heat.
Once melted, remove from heat and stir in RumChata and peppermint extract until well combined.
Pour the white chocolate mixture into the prepared baking pan and spread it evenly with a spatula.
Sprinkle half of the crushed peppermint on top of the white chocolate layer and press gently to ensure it's embedded.
In another bowl, melt the dark chocolate with coconut oil (if using) until smooth.
Pour the melted dark chocolate over the white chocolate layer and spread evenly.
Sprinkle the remaining crushed peppermint on top of the dark chocolate layer and press gently.
Refrigerate for at least 2 hours, or until fully set.
Once set, lift the bark out of the pan using the parchment paper overhang. Cut into pieces and serve.