Prepare Chocolate Layer: Line a 10 by 15-inch pan with wax paper. Melt 1 1/2 cups of chocolate and spread it over the wax paper, leaving gaps at the edges. Chill in the refrigerator to set.
Make Peanut Butter Layer: Mix peanut butter, powdered sugar, and softened butter. For easier mixing, warm this mixture in the microwave for 10-15 seconds. Spread this over the chilled chocolate layer evenly.
Add Toppings: Melt the remaining 2 cups of chocolate chips, spread over the peanut butter layer, and top with Reese’s Pieces.
Set and Serve: Allow the bark to set, then break it into pieces. Store in an airtight container.