- Preheat the oven to 180°C/gas 4. Use 1 tsp of the rapeseed oil to grease a 2lb loaf tin (approx 27cm x 12cm).
- Grate the unpeeled apples into a bowl and discard the cores.
- Add the eggs, vanilla extract, caster sugar, oil to the bowl and beat together.
- Add the flour and baking powder and mix well. Fold in the blackberries.
- Pour the mixture into the loaf tin and bake for 25 minutes until firm and golden. Cover with foil after 20 minutes if it's starting to brown too much. The cake is cooked when a knife inserted into the centre comes out clean.
- You could add other essences, such as lemon or almond, or add the grated zest of an orange or lemon.
- You could also use raspberries in place of blackberries.
- Freeze in freezer bags, wrapped in foil or greaseproof paper, for up to three months. Don't forget to label.
- Freezing instructions: Suitable for freezing once cooked. Slice then wrap in foil to freeze. You can then use slices as required.