Preheat oven to 275°. Using a greased cookie sheet, place a Hershey Kiss on each pretzel square. Place cookie sheet in the oven for about 2 minutes. All you want to do is soften the kiss. As soon as you take them out of the oven, press an M&M in the center of each kiss. Put them in the fridge or freezer to harden and then store them at room temp in an airtight container.