In a small pan melt the butter or margarine with the unsweetened chocolate. Set aside to cool slightly.
Cream together the sugar and the eggs until light in color. Add the chocolate mixture to the eggs and beat well so the eggs do not cook. Add 1 cup boiled water (still warm) and blend well. Mixture will be very liquid.
Mix together the flour, baking soda, and salt. Add this mixture to the chocolate mixture and blend well.
Mix together the vinegar and the milk and stir into the chocolate batter.
Heat donut maker that has been greased and then bake donuts according to the pans directions OR bake in a donut pan for the suggested time and degrees according to the size of your pan.
Let donuts cool on a wire rack until warm and then dip into the frosting glaze mixture.