Prepare the Cookie Dough Layer: In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until smooth and fluffy. Add vanilla extract and milk, mixing until well combined.
Gradually add the heat-treated flour and salt, stirring until a soft dough forms. Fold in 1 cup of chocolate chips until evenly distributed.
Assemble the Layers: Line an 8x8-inch baking dish with parchment paper. Press the cookie dough mixture into the dish, creating an even layer, and set aside.
Make the Chocolate Base: In a microwave-safe bowl, melt the semisweet chocolate chips and 1 tablespoon butter in 30-second intervals, stirring until smooth. Pour this melted chocolate over the cookie dough layer, spreading evenly.
Prepare the Peanut Butter Topping: In another microwave-safe bowl, melt the peanut butter with the remaining 1/2 cup chocolate chips in 30-second intervals, stirring until smooth and creamy. Pour this over the chocolate layer, spreading evenly.
Garnish and Chill: Sprinkle extra chocolate chips on top for garnish. Chill in the refrigerator for 1-2 hours, or until set.
Slice and Serve: Once firm, slice into squares and enjoy!