Add 1 (14-ounce) can sweetened condensed milk and 2 teaspoons peppermint extract to a large bowl and beat with a hand mixer until combined.
Add 4 cups of the 5 ½-6 cups powdered sugar and mix on low speed until the powdered sugar is absorbed. Increase the speed and beat until smooth. If the dough is sticky, add the remaining ¼ cup of powdered sugar. More powdered sugar may be necessary, depending on the humidity of your climate. The dough should have a soft playdough texture but not be sticky at all.
Dust a clean surface with powdered sugar and roll out the dough until it is ¼-½ inch thick, depending on how thick you’d like your patties. Use a 1-inch circle cookie cutter to cut out circles of dough. Place them on a parchment-lined baking sheet and combine the scraps of dough. Roll out the remaining dough and cut out more patties until no dough is left.
Cover the baking sheet with plastic wrap and place the patties in the fridge to chill for one hour.
When the patties are nearly done chilling, add 12 ounces semi-sweet chocolate and 2 teaspoons coconut oil to a medium-sized bowl. Heat in the microwave in 30-second increments. Stir between heating until all the chocolate is completely melted.
Use a fork to dip the chilled patties completely in the chocolate. Tap the fork on the side of the bowl to tap off the excess chocolate before transferring the pattie back to the baking sheet.
Let the patties chill for 30-40 minutes in the fridge or until the chocolate is set. Keep chilled until serving.