Line a 18x13 sheet pan with wax paper.
In a small mixing bowl, stir together the peanut butter and the powdered sugar until smooth.
Evenly space 30 Ritz crackers face down. This will be the cookies' “bottom”.
Spoon 1 tablespoon of peanut butter mixture into the center of the cracker. Do not spread the peanut butter to the edges.
Place the “top” cracker, face up. Gently press the cracker down, just until the peanut butter is close to the edge of the crackers, but not dripping over the edge.
Refrigerate the cookies on the tray for 25 minutes. (This helps firm up the peanut butter mixture).
In a medium-sized heat-safe bowl, combine 2 cups of chocolate chips.
In the microwave, heat the chocolate chips for 30 seconds at a time, stirring well after each interval, until the 2 cups of chocolate chips are melted.
Add the remaining ½ cup of chocolate chips, and stir until the chocolate is smooth.
Remove the cookies from the refrigerator.
Place 1 cookie at a time in the melted chocolate. Using a regular dinner fork, flip the cookie over until it is well coated. Slide the fork completely under the cookie and gently tap the fork against the rim or the side of the bowl, to remove the excess chocolate.
Return the sheet pan of cookies to the refrigerator. Chill for 30 minutes to help set the chocolate. Store in an airtight container.