Disappearing Brownies

I made these along with the Blonde Brownies for scout camp and they did indeed disappear.

1/2 cup butterscotch bits (more commonly known as butterscotch chips nowadays)
1/4 cup butter or margarine
3/4 cup flour
1/3 cup brown sugar, packed
1 teaspoon baking powder
1/4 teaspoon salt
1 egg
1/2 teaspoon vanilla
1 cup miniature marshmallows
1 cup semisweet chocolate pieces
1/4 cup chopped nuts

Melt butterscotch bits and butter in heavy saucepan over medium heat and cool to lukewarm.  Combine flour, brown sugar, baking powder and salt.  Stir into butterscotch mixture and then add egg and vanilla.  Mix well.  Fold in marshmallows, chocolate pieces and nuts just until blended.  Pour into well-greased 8-inch square pan.  Bake at 350 degrees 20 to 25 minutes.  Center will be soft but will become firm upon cooling.  Cut into squares.  Makes sixteen 2-inch cookies.