Line a baking sheet with parchment paper and set it aside.
In a double boiler or microwave-safe bowl, melt the white chocolate chips over low heat or in 30-second intervals in the microwave, stirring frequently until smooth.
Once melted, remove the white chocolate from heat and stir in the RumChata liqueur and peppermint extract until well combined.
Pour the white chocolate mixture onto the prepared baking sheet and spread it into an even layer using a rubber spatula. Sprinkle the crushed peppermint evenly over the top.
Refrigerate for about 20 minutes or until set.
Once the white chocolate layer is firm, melt the semi-sweet chocolate chips until smooth.
Pour the melted semi-sweet chocolate over the top of the white chocolate layer and spread it evenly.
If desired, sprinkle additional crushed peppermint over the semi-sweet chocolate layer.
Refrigerate for another 10-15 minutes or until fully set.
Once set, break or cut into pieces and serve.