Edible cups are only in a couple of the vans around the ground, they make it in a normal paper cup, which I think already has the powder in, then pour it into the edible one. As the paper cup is larger they also give you that too - that was my experience at one game earlier in the season. Seemed to be a bit of a gimmick to me, hot chocolate was so shocking we poured it away but the cup tasted ok!!
