Melt first three ingredients in double boiler. Whisk liquid ingredients in a small bowl. Put remaining ingredients in a large bowl and mix (except nuts and mallows ) Add melted choc. To liquid mixture. Pour into into dry mixture blending only to combine. Fold in nuts and marshmallows. Batter will be lumpy. Spoon into muffin cups. Bake 400 18 to 20 min until tested done. Good picnic muffin.