Cover a cookie sheet with waxed or parchment paper and spread the popcorn.
Drop the pretzels evenly over the popcorn.
Sprinkle the M&Ms next.
Microwave the white chocolate chips and shortening in a bowl for about 1 minute. Stir, then microwave in 20 second intervals, stirring well each time, until the chocolate is completely melted.
Drizzle half the chocolate over the popcorn mixture.
Gently stir the popcorn a bit, spread again, and drizzle the remaining white chocolate.
Serve immediately for a deliciously warm snack. Or let it sit out for about an hour to dry. (It’s less messy when the chocolate cools.)
Adapted from Living Well Mom.