Lightly grease and base line two 20cm/8 inch sandwich tins.
Sift the flour, cocoa powder, baking powder and salt into a mixing bowl.
Stir in the sugar.
Make a well in the flour and sugar and pour in the milk and oil, whisk together until you have a smooth batter.
Pour the batter into your prepared tins (make sure you have approximately the same in each tin)
Cook in the preheated oven for 25 - 30 mins until risen, firm to the touch, just beginning to pull away from the sides of the tin and a skewer inserted into the cakes comes out clean.
Cool in the tins for 5 minutes, then turn out onto wire cooling racks and allow to cool completely.
For the Chocolate Fudge Icing
Melt the margarine gently in a small pan.
Add the cocoa and cook for 30 seconds.
Leave to cool.
Stir in two tablespoonfuls of the milk and all the icing sugar icing sugar.
Mix well until smooth, add the extra milk if it's too stiff, it needs to be spreadable but not too liquid or it will just ooze off your cake.
Put one sponge onto a plate. If it is very domed slice off the pointy bit so you have a reasonably flat surface.
Spread one third of the fudge icing onto the cake and place the second sponge on top.
Spread the remaining fudge icing over the top of the cake.
Nutritional information is only an approximate guideline. Calculations will vary according to the ingredients you use and your cooking methods.Do wait until the cake is cool before icing or the fudge icing will slide off.