01 -
Heat your oven to 350°F and get your 8x8-inch square baking pan ready by spraying it with baking spray and lining it with parchment paper for easy removal.
02 -
Melt the butter in a small saucepan over medium heat, then remove from heat and whisk in half of your chocolate chips until completely smooth. Transfer this mixture to a large bowl and let it cool for a few minutes.
03 -
In a separate bowl, sift together the flour and cocoa powder, then whisk in the salt to ensure everything is well combined.
04 -
Add both sugars, eggs, and vanilla to your cooled chocolate mixture, whisking until the batter is smooth and glossy. Gently fold in the flour mixture until just combined, then fold in the remaining chocolate chips.
05 -
Pour your brownie batter into the prepared pan and use a spatula to spread it evenly to all corners of the pan.
06 -
Drop small spoonfuls of peanut butter across the surface of the batter, then use a knife tip or skewer to gently swirl it through the chocolate for a marbled effect.
07 -
Bake for 40-45 minutes until the center is set and doesn't jiggle when gently shaken. If the peanut butter starts browning after 25 minutes, cover with foil. Let cool completely in the pan before cutting into squares.