Sift the flour and the 2 tsp cocoa powder.
Cream the butter and sugar. Add the egg and mix thoroughly. Alternately, sift in the flour and milk.
Pour into greased pie dish.
For the sauce, begin by combining the brown sugar and cocoa powder, then sprinkle it on to the mixture in the pie dish.
Pour in the boiling water gently.
Bake at 190˚C (gas mark 5 / 375 ˚F) for 45 minutes. Serve with whipped cream.
Serving Size 4 - 6 people