Prepare the brownies: In a medium microwave-safe bowl, heat 3/4 cup chips and butter for 1 to 2 minutes until melted. Stir until smooth.
Preheat the oven to 350 degrees F. Spray a 9x9-inch pan with nonstick spray
Whisk 1 cup of the sugar, eggs and vanilla into the melted chocolate mixture.
In a separate bowl, whisk together the dry ingredients: flour, baking soda and salt. Add the dry ingredients to the chocolate mixture, stirring until combined. Spread the batter evenly in the prepared pan. Bake for 10 minutes.
In a large bowl, combine the peanut butter, 1 cup sugar and 1 egg. Drop spoonfuls of the peanut butter mixture over the partially cooked brownies. Bake for 25 to 30 minutes, or until the top is light brown and the mixture appears to be set. Let it cool in the pan. (Mine was a little gooey in the middle after 30 minutes but I took it out anyways. It then hardened well after it cools)
For the Topping: In a medium, microwave-safe bowl, heat the 1 cup of chocolate chips until they are melted and the mixture is smooth. Stir in the peanut butter and again mix until smooth. Pour the chocolate and peanut butter over the top of the brownies and spread until even. Let stand until set (or refrigerate until set). Cut into 16 chunks and serve or place in a covered container until ready to serve.