Preheat the oven to 175c/ Gas mark 4/ 350F. Mix together the mashed banana, apple puree, eggs and agave nectar in a bowl. Mix the spelt flour and baking powder and then add the banana and apple mixture and mix well. When the dry and wet ingredients are combined, gently stir through the berries.
Spoon into a lined 500g/ 1lb baking tin and bake for 45 min to 60 min. Test with a skewer and remove from the oven when the skewer comes out clean.