Begin by lining a 9x13-inch baking pan with aluminum foil. Set aside.
In a microwave-safe bowl, add peanut butter, chocolate chips, butter, and vanilla extract. Microwave in 30-second increments, stirring in between, until fully melted and smooth.
Add the crushed pretzels and confectioners' sugar. Beat with an electric mixer to blend. When mixed, press into the prepared baking pan to form an even layer.
Then, in a microwave-safe bowl, add 2 cups of chocolate chips. Microwave in 30-second increments, stirring in between, until fully melted and smooth. Pour over the prepared cookie base.
Immediately top with pretzels, pressing them into the chocolate. Then decorate with sprinkles.
Set aside for 1-2 hours to make sure it's completely set.* With a sharp knife, cut into 2-inch squares. Pack and store in an airtight container.