01 - Preheat the oven to 350°F. Line an 8x8-inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a large bowl, whisk together melted butter and sugar until smooth. Add eggs and vanilla; whisk until well combined. Sift in cocoa powder, flour, and salt. Mix until just combined—do not overmix.
03 - Spread batter evenly into the prepared pan. Bake for 22–25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Cool completely in the pan.
04 - In a medium bowl, beat together peanut butter, melted butter, powdered sugar, vanilla, and salt until smooth and creamy. Spread evenly over the cooled brownie base. Refrigerate for 30 minutes to set.
05 - Place chocolate chips in a heatproof bowl. Heat heavy cream until just simmering, then pour over chocolate. Let sit for 2 minutes, then stir until smooth. Let cool slightly, then pour and spread over the peanut butter layer.
06 - Refrigerate for at least 1 hour, or until set. Lift brownies from the pan using parchment overhang. Cut into squares and serve.