Preheat the oven to 180°C, gas mark 4. Base line a 22cm square tin.
Whisk the eggs and sugar together until pale and creamy. Sieve the flour and cocoa together and gently whisk into the eggs, then whisk in the oil.
Pour into the prepared tin, scatter over the cranberries and chocolate chips if using. Bake for 25-30 minutes. Cool slightly before turning out of the tin. Cut into 12 pieces.
Replace the cranberries with any other dried fruit such as apple or chopped dates. For an extra healthy option, replace the flour with self-raising wholemeal flour.
Freezing and defrosting guidelines
Bake according to the recipe but stop before adding decoration or icing if called for. Allow to cool completely. Wrap well in clingfilm and tin foil (to prevent freezer burn) and freeze for up to 3 months.
Loosen the tin foil and clingfilm but leave to defrost in packaging at room temperature for several hours before serving. If you wish to serve the baked goods warm, place them on a baking sheet for 10 minutes in a moderate oven.
If you wish to add icing or decoration, add them after the baked goods have fully defrosted and are at room temperature.