Chocolate sheet cake

Method

• step 1

  Preheat oven to 180c/350f/gas 4. Grease a 30 by 20 roasting tin.Line the base and sides with non-stick baking paper.

• step 2

  Whisk egg whites until stiff peaks form. Sift the flour and cocoa into a seperate bowl. Add egg yolks,marg,caster sugar and milk. Beat with a electric whisk or wooden spoon for 2 mins, until smooth.

• step 3

  Fold in the egg whites.Spoon the mixture into the tin. Bake for 35-40 mins, or until firm in the centre.Cool completely in the tin.

• step 4

  For the icing, put the chocolate and 5 tbsp of water into a pan and heat gently until melted. Beat in the icing sugar and oil until smooth.

• step 5

  Turn out cake and spread the icing on top with a palette knife. Cut into squares and enjoy!