In a large saucepan, mix the powdered sugar and flour.
Whisk in the heavy whipping cream.
Cook and stir over medium heat until the mixture thickens and bubbles.
Reduce the heat to low and continuously stir 2 additional minutes.
Remove the saucepan from the heat and stir in the vanilla and rum extracts, followed by the pistachio and candied cherry pieces.
Allow the mixture to cool completely, then mix in the mini chocolate chips.
Use a 1 Tablespoon cookie scoop to ball and drop the dough onto a cookie tray lined with a silicone baking mat or parchment paper.
Bake for 10-12 minutes, until the edges begin to golden, then remove the trays from the oven to cool.
Allow the cookies to remain on the trays for 10 minutes, then transfer them to a cooling rack to cool completely.
Using a double boiler technique, melt the chocolate wafers. Stir frequently.
Use a small spoon to spread a layer of the melted chocolate onto the bottom of each cookie. Set the cookies upside-down while the chocolate completely cools.