Place pretzels on a microwavable plate. Place an unwrapped Hershey's kiss on each pretzel square.
Microwave for just enough seconds** (see below) to start to melt the chocolate enough that an M & M can be pressed into the top of the Hershey's kiss.
**(My microwave takes 47 seconds, then I let them stay on the warm plate for another 30 seconds or so before pressing in the M & M. If the M & M doesn't go down easily, leave it & work on another before coming back to the stubborn M & M.)
Only do a few at a time so that the chocolate doesn't have time to harden again.
Cool on a cooling rack (or 10 minutes in the freezer) & store in an air-tight container until ready to serve.
ANOTHER GREAT IDEA: Use Hershey's Hugs in place of the Hershey's Kisses. The stripes look very festive!