Combine powdered sugar, cocoa powder, sweetened condensed milk, peppermint extract, and salt in a mixing bowl. Mix until a smooth dough forms.
Shape the dough into a log about 1 inch in diameter, wrap in plastic wrap, and refrigerate for at least 30 minutes.
Slice the log into 1/4-inch thick rounds and place on a parchment-lined baking sheet.
Melt chopped chocolate and coconut oil in a microwave-safe bowl in 30-second intervals, stirring until smooth.
Dip each round into the melted chocolate, allowing excess to drip off, and return to the baking sheet.
Refrigerate the coated patties for another 30 minutes to let the chocolate set.