Start by lining a baking sheet with wax paper.
Use a table knife to spread peanut butter between 2 Ritz Crackers, sandwiching the crackers together.
Set each Ritz cookie on the wax paper lined baking sheet, in preparation for dipping.
Add the chocolate to a microwave-safe measuring cup or bowl; and melt, starting at 30 seconds, then stirring every 15-20 seconds, 'til melted and smooth.
Using 2 forks or tongs, dip each cracker sandwich in the melted chocolate; shake any excess chocolate off before placing back on the wax paper to dry. If using, add nonpareil sprinkles to the top before the chocolate dries.
When all the Ritz crackers with peanut butter have been dipped, chill them in the freezer for about 15 to 20 minutes.
Remove them from the freezer, and store your Ritz cracker cookies in between two layers of wax paper in an airtight container in the fridge for up to 2 weeks.