Preheat oven to 180°C/350°F. Grease and line 2 x 8”(20cm) round cake pans with baking paper.
Tear the kale leaves into bite-sized pieces and boil or steam for 3-5 minutes until tender. Refresh by running under cold water, drain and squeeze out the excess liquid.
Add the kale to a blender (or a large bowl and use a stick blender) with the eggs, oil, vanilla, applesauce and sugar and whiz until smooth.Note: if you've made this kale cake recipe before, you'll have been instructed to puree the kale with a stick blender, then stir it into a bowl of beaten egg, oil, applesauce, vanilla ,and sugar. I've tested it again many times and although you can do it that way, it's easier to blend the kale with the liquid ingredients.
Pour the blended kale mixture into a mixing bowl. Squeeze the excess moisture out of the grated apple, then add the apple to the bowl and stir to combine.
Sift in the flour, baking powder and salt and gently combine, taking care not to overmix at this stage.
Pour into the prepared pans and bake for 20-25 minutes or until an inserted skewer comes out clean.
Cool for 2 minutes in the pans and then turn onto a wire rack to cool completely.
For the apple frosting
Beat the butter, apple sauce and vanilla, then sift in the powdered sugar and beat until thick and smooth. If necessary, add a little more powdered sugar to thicken, or a tablespoon of milk to thin.
Frost the completely cooled cake. And, if desired, decorate the top wiht blueberries.
If you don't have applesauce, just peel, core and slice some apples, steam until soft and puree.
Readers have had success using flax eggs to make a vegan kale cake.
Use any apples that you like to eat.
Fresh kale can produce a more vibrant colour, though supermarket bags of chopped kale still work well.
Don't be tempted to add more kale to get a brighter colour or the flavour will come through too much.
NOTE: I previously had the method written telling readers to puree the kale, then beat it into the batter. However, some people didn't puree it enough so the color wasn't so green. I've been testing and now amended the recipe to puree the kale with the other wet ingredients in a blender. That ensures the kale is fully pureed and the kale is very green!