9 bars

How to Make It

Step 1

Preheat oven to 350°F. Butter an 8-inch, square pan and line with parchment paper.

Step 2

Melt half of butter and then mix with crumbs, brown sugar and a pinch of salt. Press firmly into bottom of pan. Bake in bottom third of oven until set, 10 to 12 minutes.

Step 3

Combine remaining butter and unsweetened chocolate in a heatproof bowl; microwave at 20-second intervals until melted, stirring after each interval. Cool slightly. In a separate bowl, whisk sugar, vanilla and eggs. Stir in chocolate mixture. Add flour and mix until just combined. Pour over cooled crust and bake until just set, 22 minutes.

Step 4

Remove from oven. Set broiler on high and place oven rack 3 inches from heat. Sprinkle marshmallows and chocolate chips over cookie and broil until marshmallows start to brown, 1 minute. Remove from oven and let cool before cutting into squares.

Ratings & Reviews

slocook1's Review

May 23, 2014
I gave these 5 stars because I was able to omit the marshmallows which I absolutely can't stand. They came out perfect. The next time I'm going to do as a previous reviewer did and use peanut putter for a Reeses effect.

momshome's Review

September 09, 2009
Sooo good as is but took it to another level. For p-nut butter lovers...after removing crust from the oven, place 1/3 cup p-nut butter & 1 TBLS. butter into mike till pourable, about 20-30 sec.) Pour over crust, then proceed with rest of yummy recipe. Will make over & over, sometimes p-nut free, others with p-nut butter.