01 -
Preheat oven to 350°F. Line 8x8 metal pan with parchment paper along sides and bottom.
02 -
Layer graham crackers on bottom of pan, breaking pieces to fill gaps.
03 -
Microwave butter and chocolate chips in 30-second intervals until melted and combined.
04 -
Stir in sugar, microwave 1 minute more. Let cool 5 minutes if needed.
05 -
Vigorously stir in eggs for one minute until ribbony. Add vanilla, cocoa powder, salt, and flour until combined.
06 -
Pour batter over crust and bake 25 minutes.
07 -
Top with marshmallows, graham crackers, and chocolate. Bake 8-10 minutes more.
08 -
Cool in pan 1 hour before lifting out and cutting.