• Preheat your oven to 350°F. Line a 9"x13" brownie pan with non-stick foil.

Brownie Batter

• Place the chocolate, butter and espresso powder in a medium, microwave safe bowl. Use the melt chocolate function on your microwave, or heat for 1 minute, stir, and continue to heat in 30 second intervals (stirring in between) until fully melted and smooth. (You can also use a double boiler for this step)
  226 g bittersweet chocolate chopped, 165 g butter, ½ tsp espresso powder
• In a small bowl, whisk together the flour, cocoa powder and salt. Set aside.
  80 g flour, 16 g cocoa powder, 2 g salt
• In a large bowl, on low speed, beat together the eggs, egg yolk, sugar, brown sugar and vanilla until the sugar is dissolved and the mixture is a thick, glossy, syrup.
  3 eggs, 1 egg yolk, 134 g sugar, 74 g brown sugar, 15 ml vanilla
• Stir the melted chocolate mixture into the egg and sugar mixture until uniform in color and consistency.
• Add the flour mixture and fold just until no more dry ingredients are visible.
• Fold in the peanut butter chips, semisweet chocolate chips and chopped peanut butter cups. Set the brownie batter aside.
  80 g peanut butter chips, 80 g semisweet chocolate chips, 80 g peanut butter cups

Cookie Batter

• Add the butter and dry milk powder to a medium saucepan. Cook over medium low heat until the milk solids are golden brown and have a rich, nutty aroma. Immediately transfer to a large mixing bowl.
  224 g butter, 16 g dry milk powder
• Add the brown sugar, sugar, vanilla and salt to the browned butter, whisk to combine and start the sugar melting. Let rest until cooled to room temperature.
  165 g brown sugar, 150 g sugar, 15 ml vanilla, 2 g salt
• Beat in the eggs and egg yolks on low speed until the sugar is dissolved and the mixture is thick and syrupy.
  2 eggs, 1 egg yolk
• Stir in the flour until no dry ingredients are visible.
  240 g flour
• Fold in the peanut butter chips, semisweet chocolate chips and chopped peanut butter cups.
  80 g peanut butter chips, 80 g semisweet chocolate chips, 80 g peanut butter cups

Assembly

• Add alternating scoops of brownie batter and cookie batter to your prepared pan, attempting to get roughly equal distribution of the two batters. Pipe the caramel, peanut butter and hot fudge in thick lines or zig-zags over the surface of the batters. Use a butter knife to lightly swirl the batters and toppings together (the mixture may clump and drag a bit rather than smoothly swirling, that is ok, it well melt and merge in the oven). Gently tap and shake the pan to settle the batter more evenly in the pan.
  120 ml caramel ice cream topping, 128 g creamy peanut butter, 120 ml hot fudge
• Place the pan in the preheated oven for about 34 minutes. The edges will be set, the top will be dry and slightly glossy in between the swirl topping, the swirl topping will be tacky and may bubble up at the edges, the middle will appear a little loose if you shake the pan - be careful not to overbake or the brookies will be dry.
• Allow the brookies to cool completely before slicing into 24 large or 40 small bars.