•1/4 teaspoon baking powder
•1/4 teaspoon salt
•4 1/2 tablespoons unsalted butter
•1/2 cup plus 1 tablespoon unsweetened cocoa powder, preferably natural
•1 1/4 cups sugar
•1 large egg
•2 large egg whites
•2 teaspoons vanilla extract
•8 regular size marshmallows
•2/3 cup coarsely chopped walnuts or pecans
•1/3 cup chopped chocolate chips
•1 cup less 1 tablespoon all purpose flour
1. Line the bottom and sides of an 8 inch square baking pan and with foil and parchment paper coated with cooking spray. Remember to leave enough of an overhang to pick up the brownies out of the pan with the liner. (If you don't plan on letting the batter rest at the end of step 3 before baking, position a rack center over and preheat to 350 F.
2. Thoroughly whisk flour, baking powder and salt in small bowl
The batter may be thick but that's how it's supposed to be.