Add powdered sugar, extract, and sweetened condensed milk into the large bowl (or stand mixer). Using a wooden spoon (or paddle attachment), mix the dough until it is the consistency of playdough. It should be easy to form and not overly sticky or dry. If it is too sticky, add a little powdered sugar until moldable. If it is too dry, add a little more milk until moldable.
Once the dough is ready, transfer it to a parchment-lined or sprinkled (with powdered sugar) dough board. Using a rolling pin, roll out the dough until it ½" thick circle or oval.
Carefully cut out the mini circles with the cookie cutter and use a spatula to transfer the dough rounds to a parchment-lined baking sheet. Repeat until all circles have been cut out. You will need to re-roll the dough scraps to make more.
Once all rounds are on the the parchment-lined baking sheet, cover and freeze for 1 hour. You will need these to be firm so they do not melt in the warm chocolate.
Add milk chocolate morsels and shortening to a microwave-safe bowl. Melt in 30-second intervals until chocolate is creamy. Once done, allow it to sit for one minute to cool down.
Remove dough rounds from the freezer. Using a fork, dip each into the chocolate, and shake off any excess chocolate. Transfer to a parchment-lined sheet. Repeat until all rounds are coated. Once they are coated, transfer the sheet to the refrigerator for 10 minutes.
Once patties are hardened, it is time for the (optional) white chocolate swizzle. Add the white chocolate morsels to a microwave-safe bowl. Melt in 30-second intervals until chocolate is creamy. Once done, allow it to sit for one minute to cool down. Add melted chocolate to a zippered bag, snip the edge, and swizzle the melted chocolate over each chocolate covered patty.
Return the patties to the refrigerator until chocolate is hardened. Once firm, transfer patties to an air tight container. Line each level of patties with parchment paper to keep them from possibly sticking to one another. Store in the refrigerator in an airtight container for up to 2 weeks.