Line a full or half-sheet pan with parchment 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 cookie’s “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 30 to 45 minutes.
In a medium-sized heat-safe bowl, add combine 2 cups of the white 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 chips are melted.
Add the remaining ½ cup of white 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 dinner fork or chocolate dipping tool, 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.
Place the dipped cookie back onto the parchment paper.
Return the sheet pan of dipped cookies to the refrigerator. Chill for 30 minutes to help set the chocolate. Store in an airtight container.