In a mixing bowl, combine powdered sugar, sweetened condensed milk, and peppermint extract. Stir together until the mixture transforms into a smooth, dough-like consistency, which should take about 3-4 minutes.

Using your hands, scoop out small portions of the filling and roll them into balls, then flatten each ball into discs about ¼-inch thick. Place the shaped patties on a lined baking sheet, then refrigerate for 15-20 minutes.

While the peppermint patties chill, combine the dark chocolate chips in a microwave-safe bowl. Melt the chocolate in the microwave in 30-second intervals, stirring after each interval until smooth.

Once the peppermint discs have chilled, dip each disc into the melted chocolate, making sure it is completely coated. Allow excess chocolate to drip back into the bowl.

After all patties are coated, sprinkle with festive decorations like crushed candy canes or colored sprinkles. Allow the chocolate to set at room temperature for about 30 minutes.