Preheat oven to 350.
Line an 8 inch pan with tin foil, leaving foil hanging over the sides.
Spray pan with non stick cooking spray.
Place graham crackers into food processor and pulse until crackers are turned into crumbs.
Melt 4 tablespoon butter in the microwave.
Pour melted butter into food processor.
Add in 1 tablespoon sugar, 1/4 teaspoon salt, and pulse to combine. Press mixture firmly into bottom of 8 inch pan.
In a large bowl, melt chocolate chips with remaining butter (6 tbsp).
Once melted and combined, allow to cool about 10 minutes, stirring every few minutes.
Add in remaining sugar (1/2 cup), eggs, espresso powder, vanilla extract, and 1/4 teaspoon salt.
Add in flour and baking powder. Stir until smooth.
Pour batter over crumb layer in baking pan.
Place pan in oven and cook about 30-35 minutes, or until toothpick comes out clean once inserted in middle.
Remove from oven and sprinkle marshmallows on top.
Use your torch to slightly toast the tops of these. *You can also set oven to broil and place pan back in oven. Allow them to broil for about 2-3 minutes, or until golden brown.
Allow pan to cool about an hour or so before removing foil from pan.
Lift sides and place brownies on flat surface. Carefully cut into bars.
Serve and enjoy!