Preheat oven to 375°F Spray a 9-inch square baking pan with nonstick spray.
For the crust, combine chocolate wafers, butter, and sugar in a food processor and pulse to combine until cookies are evenly crushed and combined with other ingredients.
Press crust mixture firmly into the bottom of a prepared baking pan. Bake for 8 minutes, then set on a rack to cool completely.
Make the filling by combining brown sugar, confectioners sugar, butter, peanut butter, and salt. Mix until just combined (do not whip). Put the bowl in the refrigerator.
Make the ganache topping by combining the chocolate chips and cream in a microwave-safe bowl. Cook in the microwave at medium power (50%) for 60-90 seconds. Stir until the bowl no longer feels warm. Continue heating at 15-30 second intervals, stirring until smooth and melted. Do not overheat!
Spread about 1/4 cup of chocolate mixture evenly over cooled crust. Place pan in freezer until chocolate is set, about 5-10 minutes.
Spread peanut butter mixture into even layer over chocolate. Give chocolate ganache a quick stir to smooth any lumps, then spread evenly over top of peanut butter layer.
Cover pan with plastic wrap and place in freezer for 1 hour to set. When firm, use a sharp knife to cut into squares. Keep refrigerated and serve cool.