Heat ½ cup of the chocolate chips and the butter over low heat until melted; cool. Heat oven to 375º. Mix flour, sugar, baking powder, vanilla, salt, eggs and chocolate with marshmallows and nuts and remaining chocolate chips. Bake until marshmallows are golden brown and wooden toothpick inserted in the center comes out clean, 15 to 20 minutes. Cool completely; cut into 2 x 1 inch bars. Makes 36 brownies.
Enjoy this yummy gooey dessert!