This is sooo good! I, too, only added 1/2 c sugar. I never use half and half so I decided to use evaporated milk instead.
I didn't want to waste the other 8 oz of evap milk so I just poured the 12 oz can into a 4 c measure and then filled with milk and heated it all. I didn't bother with adding some cold milk to the hot chocolate. Yum Yum, just what I wanted on a cool morning.