Preheat oven to 350°F (177ºC). Line an 8×8-inch pan with parchment paper.
Bloom the cocoa: In a large bowl, whisk the melted butter (1 cup), brown sugar (1 1/2 cups), granulated sugar (1/2 cup), espresso powder (1/2 teaspoon), and cocoa powder (2/3 cup) until smooth and glossy.
Add eggs and flavorings: Whisk in the eggs one at a time until fully incorporated. Add vanilla (2 teaspoons) and salt (1/2 teaspoon).
Add flour: Sprinkle flour (1/2 cup) over the batter and whisk just until no streaks remain. Fold in the chocolate chips (1/2 cup).
Bake: Spread the batter into the prepared pan. Bake 25–30 minutes, or until edges are set and the center looks slightly soft. A toothpick should come out with a few moist crumbs.
Cool completely: Allow brownies to cool in the pan at least 60 minutes, or chill 20–30 minutes.(Warm brownies will melt the peanut butter layer.)
Make the Peanut Butter Layer
In a medium bowl, beat together the peanut butter (1 1/2 cups), powdered sugar (1 1/4 cups), softened butter (1/4 cup), heavy cream (2–3 tablespoons ), vanilla (1/2 teaspoon), and a pinch of salt until smooth and creamy.Spread over the cooled brownie layer. Refrigerate 15–20 minutes.
Add the Chocolate Topping
Melt chocolate chips (1 cup) with 1 teaspoon oil (or 1 tablespoon butter) in the microwave in 20–30 second bursts, stirring between intervals, until smooth.Pour and smooth over the peanut butter layer. Chill 15 minutes, or until the chocolate is set but sliceable.
Notes
Let each layer cool fully. Warm brownies → melted PB layer → messy slices. Give each layer its moment.
Don’t rush the chilling time. Those two short chilling periods are what give you crisp chocolate, creamy PB, and neat squares.
Avoid the microwave. It melts the topping layers and can ruin the texture.
Use parchment + overhang. Makes it so easy to lift the whole slab out in one piece. Serve chilled. The chocolate topping has the best crunch straight from the fridge.