Rocky Road Frosting

2 squares bitter chocolate
2 cups miniature marshmallows, divided
1/4 cup water
1/4 cup butter
2 cups sifted confectioners' sugar
1 teaspoon vanilla extract
1/4 cup chopped walnuts or pecans

In small saucepan, place chocolate, 1 cup marshmallows, water and butter. Heat over low heat, stirring until blended. Cool slightly. Add sugar and vanilla extract, beating until smooth and slightly thick, about 2 minutes. Stir in reserved cup of marshmallows and nuts.