Preheat oven to 350 degrees.
Grease a square 9 x 9 inch pan.
Mix Bisquick, sugar, cocoa, 1/4 cup margarine, 1 teaspoon vanilla, and eggs.
Spread in pan.
Bake 30 to 35 minutes or until toothpick inserted in center comes out clean.
Immediately sprinkle with marshmallows. Drizzle with topping.
Sprinkle with 1/2 cup chocolate chips and the peanuts.
Mix 1/2 cup chocolate chips, 2 tablespoons butter and the whipping cream in 1-quart saucepan over low heat.
Stir constantly, until chocolate and butter are melted. Remove from heat.
Stir in powdered sugar and 1 teaspoon vanilla until blended.
Pour evenly over brownies.
Refrigerate about 2 hours or until topping is firm.
Cut into bars.