Peanut Butter Brownies

Preheat the oven to 350°F with a rack in the center. Line a 9" x 13" baking pan with parchment, leaving a slight overhang for easy removal, and lightly grease the parchment.  

To make the batter: In a large bowl or the bowl of a stand mixer fitted with the flat beater, add the eggs, cocoa, peanut butter, vanilla, salt, baking powder, and espresso powder. Beat to form a thick, uniform paste, scraping the bowl as needed. 

In a saucepan set over low heat (or a medium microwave-safe bowl), melt the butter, then add the sugar and stir to combine. Continue to heat (or microwave) briefly, just until the mixture is hot but not bubbling (about 110°F to 120°F); it’ll become shiny as you stir. Add to the egg mixture and stir until smooth and shiny. 

Add the flour and stir just until a few dry streaks remain.  

Add the peanut butter chips and stir until well combined. 

Transfer the batter to the prepared pan and smooth into an even layer. It will be slightly thicker than some brownie batters; that’s OK.  

To make the peanut butter swirl: In a small bowl, stir the peanut butter and sugar to combine (the sugar will not dissolve). Dollop the mixture on top of the brownie batter and use a butter knife or wooden skewer to swirl it gently, creating a marbled effect. Sprinkle with additional peanut butter chips if desired.

Bake the peanut butter brownies for 28 to 32 minutes, until the edges feel set and a toothpick or the tip of a sharp knife inserted into the center comes out with moist crumbs clinging to it but no raw batter. A digital thermometer inserted in the center should register 205°F when the brownies are done.

Remove the brownies from the oven and let cool in the pan on a rack. Use the parchment to lift the brownies out of the pan and transfer them to a cutting board for slicing. 

Storage information: Store leftover peanut butter brownies in an airtight container at room temperature for several days; freeze for longer storage.