Disappearing Marshmallow Brownies
["1/2 c. butterscotch bits", "1/4 c. butter or margarine", "3/4 c. flour", "1/3 c. firmly packed brown sugar", "1 tsp. baking powder", "1/4 tsp. salt", "1/2 tsp. vanilla", "1 egg", "1 c. miniature marshmallows", "1 c. semi-sweet chocolate bits", "1/4 c. chopped nuts"]
["Melt first 2 ingredients in a 3-quart saucepan over medium heat, stirring constantly.", "Remove from heat and cool to lukewarm. Then add flour, brown sugar, baking powder, salt, vanilla and egg. Mix well.", "Add marshmallows, chocolate bits and nuts.", "Fold into batter until just combined, about 5 strokes.", "Spread in a greased 9-inch pan.", "Bake at 350\u00b0 for 20 to 25 minutes.", "Do not overbake. Center will be jiggly when done but will be all right when cool."]
["butterscotch bits", "butter", "flour", "brown sugar", "baking powder", "salt", "vanilla", "egg", "marshmallows", "semi-sweet chocolate bits", "nuts"]