In a large mixing bowl, combine powdered sugar, sweetened condensed milk, melted butter, and peppermint extract. Mix thoroughly until smooth.

Dust your hands with powdered sugar, take small amounts of the filling, and shape into discs about 1/2 inch thick.

Refrigerate the shaped filling for at least 30 minutes until firm.

Melt dark chocolate in a microwave-safe bowl, heating in 30-second intervals while stirring until smooth.

Dip each chilled patty into the melted chocolate using a fork, ensuring it's fully coated, then place back on the tray.

Let the chocolate set at room temperature for about 30 minutes, then decorate with sprinkles or candy canes if desired.