• Preheat to 350°F. then line an 8x8-inch metal pan with parchment and set aside.
• In a heatproof bowl, combine butter, chopped chocolate, and oil. Melt gently (microwave in 30 sec bursts or over a double boiler), then stir in cocoa powder and the espresso powder until smooth. Let it cool slightly.
  ½ cup butter, 3 tbsp neutral oil, 4 oz 70% dark chocolate, chopped, 2/3 cup Dutch process cocoa powder, 1 tsp instant espresso powder
• In a large bowl, beat eggs, yolk, granulated sugar, powdered sugar, and vanilla on high speed for 3-6 minutes until thick, pale, and ribbon-y. This is where that shiny crackle top is born!
  2 large eggs , 1 egg yolk, 1 cup granulated sugar, ½ cup powdered sugar, 1½ tsp vanilla extract
• With the mixer on low, slowly pour in the slightly cooled chocolate-butter mixture.
• Sift the dry ingredients into the brownie batter mixture. Gently fold into the batter with a spatula.
  ½ cup all-purpose flour, 1 tbsp cornstarch, ½ tsp kosher salt
• Pour the batter into the prepared pan, smooth the top, and tap the pan once on the counter. Bake 23-25 minutes, or until a toothpick comes out with moist crumbs
• Let the brownies cool completely in the pan before adding any toppings. Adding the peanut butter layer to warm brownies will cause it to soften and lose structure.

Peanut butter layer

• In a medium bowl, whip together the softened butter and peanut butter using a hand mixer until smooth and fluffy.
  5 tbsp butter, 3/4 cup peanut butter
• Add the powdered sugar, vanilla extract, and salt, and mix until the mixture becomes crumbly but cohesive, it should hold together when pressed.
  1 & 1/2 cup powdered sugar, 1/2 tsp vanilla extract, 1/4 tsp salt
• Once the brownies have cooled, crumble the peanut butter mixture over the cooled down brownie then press that mixture evenly over the surface of the brownies. Use a piece of wax paper or parchment paper to help press it down smoothly and evenly without sticking.

Make the chocolate topping

• In a microwave-safe bowl, melt the butter and chocolate chips in 20–30 second intervals, stirring between each, until smooth and glossy. Let it cool for about 5 minutes so it doesn’t melt the peanut butter layer.
  5 tbsp butter, 1 cup semi-sweet chocolate chips
• Pour the melted chocolate over the peanut butter layer and spread it out gently with an offset spatula. If desired, drizzle some extra melted peanut butter over the top for a pretty swirl or decorative finish.
• Refrigerate the brownies for about 30–60 minutes to set the layers before slicing. Store in the fridge for the cleanest cuts!