INGREDIENTS
1 stick
unsalted butter
12 oz
semisweet chocolate bars or semisweet chocolate chips
1 1/2 cups
flour
1/4 cup
unsweetened cocoa powder
1 1/2 tsp
baking powder
1/4 tsp
salt
1 1/4 cups
(packed) light brown sugar
3
eggs, at room temperature
1 1/2 tsp
pure vanilla extract
30
marshmallows
7 1/2 oz
semisweet chocolate bars cut into ½ inch squares for garnish