combine sugar and cocoa in a sauce pan and mix to break up cocoa clumps

add canned milk and stir

cook on high, stiring constantly (watch carefully because this stuff boils oven easily)

bring to a vigorous boil and turn heat down to low

simmer, stirring occasionally until sauce thickens slightly...between 15 and 30 minutes usually

remove from heat and serve hot over ice cream

NOTE: If you want to eliminate the butter and use low fat canned milk to reduce calories, it's still delicious.