Make cake mix by directions on the back of the box, mixing by hand with a spoon.
Pour batter into an oven safe dish.
Into measured boiling water add cocoa and sugar, stirring to dissolve sugar.
Pour the cocoa mix over the back of a tablespoon over the batter mix (so pouring doesn't pit the batter). The sauce will sink to the bottom, when cooked.
Bake for approx 25 mins checking with a skewer only the batter depth.
When done leave to cool for a few minutes. Dust with a little icing sugar if you wish. Serve with ice cream.
Notes
I use a $0.70c home brand cake mix for this. (2023 and it's now $0.90c)This is easy and cheaper than a self saucing pudding box mix.Can be frozen.Can make as individual servings, may need extra sauce ingredients. If individual leave room for ice cream in bowl when this is cooked.