01 -
Preheat oven to 350°F (175°C). Spray an 8x8 inch square baking pan with baking spray and line with parchment paper.
02 -
Melt butter in a small saucepan over medium heat. Remove from heat, whisk in 87g (½ cup) chocolate chips until fully melted. Transfer to a large bowl and let cool briefly.
03 -
In a separate bowl, sift together flour and cocoa powder. Whisk in salt until evenly incorporated.
04 -
Whisk both sugars, eggs, and vanilla into the melted chocolate mixture until smooth and well combined.
05 -
Fold the flour mixture into the wet ingredients until just combined, then gently fold in remaining chocolate chips.
06 -
Pour batter into prepared pan. Drop peanut butter by teaspoonfuls over the top and swirl gently with a knife or skewer to create a marbled effect.
07 -
Bake for 40-45 minutes until center is set. Cover with foil after 25 minutes if peanut butter browns too quickly. Let cool completely before cutting into squares.