Line several baking sheets with parchment paper.
Combine 2 cups of confectioners sugar & all of the sweetened condensed milk in mixer bowl.
Beat with paddle attachment until well incorporated.
Add flavoring & remaining confectioners sugar, 1/2- 1 cup at a time- beating inbetween until dough is stiff but still pliable.
Roll the dough into a log, wrap in plastic wrap & freeze for about 30 minutes.
Remove & slice into rounds & place on prepared parchment lined baking sheets.
Return to freezer for another 15 minutes.
Temper the chocolate coating by combining the chocolate & shortening in a medium glass bowl.
Microwave in 30-second increments on medium power, stirring inbetween each increment until melted & smooth.
Dip one pattie at a time into the chocolate using a fork, tap the fork on the side of the bowl to shake off any excess chocolate.
Place back on cookie sheet & repeat until you have coated all the patties.
Return to freezer for 10 minutes to set the chocolate.
Store in refrigerator.