S'mores Cookies 11 Steps
Place butter in a medium saucepan over medium heat, stirring often, until it foams, then browns, 5-8 minutes. The butter can burn easily after it foams so watch carefully and be prepared to take off the heat. Set aside and let cool.
In a mixing bowl, add your two types of flour, baking soda, espresso powder and kosher salt together and whisk until evenly combined. You can make espresso powder by grinding coffee beans and sifting it so it is extremely fine with no coarse pieces.
In your stand mixer or another mixing bowl, add sugars (brown and granulated) and browned butter together and beat on medium speed for about 1 minute until incorporated.
Add your eggs and vanilla and mix for another minute. The mixture should thicken and lighten at this point.
Reduce speed of stand mixer or electric hand mixer and add dry ingredients and beat just to combine. Mix in chocolate chips with a wooden spoon or rubber spatula and half of the chopped milk chocolate bar and half of the chopped graham cracker cookies.
The dough will be quite soft so to hydrate the flour and allow to thicken, place dough in fridge for 1 hour.
Place a rack in the middle of the oven; preheat to 375°F. Scoop with 1/4 cup or ice cream scoop. These make about 10-12 large cookies.
Make a hole and place a single large marshmallow into the middle of every cookie dough ball, making sure to leave part of the marshmallow sticking up through the middle of the cookie dough ball. Top cookie dough ball (around the marshmallow) with remainder of chopped milk chocolate and chopped graham cracker. It will look crowded but cookies spread significantly and toppings will space out. Place these loaded cookie dough balls back into the fridge for 20 minutes as they may have softened during the reshaping and insertion of marshmallow process.
After 9-10 minutes of baking, cookies are not fully done yet but turn your oven to the broil setting and broil cookies on high for 1 minute to 1 minute 30 seconds. Watch carefully so cookies do not burn while broiling.
Once marshmallow is toasty and cookies are more cooked (it will have gained some more colour after broiling), let cool on baking sheets for at least 20 minutes. While the cookies are still hot you may have to squish down the marshmallow slightly as it tends to rise (puff up) in the oven after broiling. When cool enough, carefully use spatula to transfer to a wire rack and let cool completely. Repeat with remaining dough and a fresh aluminum foil-lined cooled baking sheet.