Per request, I am posting this frosting separately so people can just search for frosting. This is my family tested Dobash recipe. Don't let the richness fool you. We love this frosting for it's light and just right sweetness. I have also posted the full recipe for the cake with the frosting. I hope you like it as much as we do!
In a saucepan, combine sugar, 1-1/2 cups of the water, butter and salt. Stir and bring to a slow boil and lower heat to medium.
In a separate small bowl, combine the remaining water with the cornstarch and cocoa. Stirring until smooth, add to hot mixture, whisking constantly to avoid lumps, until smooth and thick. Remove from heat and continue stirring until cool.