In a bullet/blender or food processor add the pitted prunes, eggs, vanilla and oil and blitz until well blended.
Sift cocoa and flour into a bowl, add sugar. Empty the prune mix into the flour bowl and mix until just combined.
Spread mixture into a lined square cake tin approx 18x18cm. The mix is thick and tacky so it may take a bit to spread it around.
Bake for about 23-25 minutes or until just baked. Cool in the tin then turnout onto a wire rack. Dust with icing sugar before serving.
Notes
Sprinkle on or add chopped walnuts if you wish.Play with the prune / sugar ratio if you wish to lessen the sugar more.These freeze well and actually are really fudgy if eaten straight from the freezer.