Dry roast the walnuts. Since they burn easily if you roast them after breaking them up, roast them, let them cool down a little, then break them up by hand. (Set some aside for topping.)
Chop the apple into small bite-sized pieces that are mix easily into the batter. Heat the ingredients marked ★ in a saucepan over medium heat. When it comes to a boil, reduce the heat to low and cook out the moisture.
In a bowl, mix the olive oil, maple syrup and the cooled mixture from Step 2. Stir in the soy milk.
Fold in the cake flour, baking powder, and brown sugar. Add the walnuts. (Don't add the walnuts you set aside for decoration.)
Pour the batter into the muffin cups.
Top with the remaining walnuts. (The muffins will rise when baking, so lightly press them down into the batter.)
Bake for 20 minutes in an oven preheated to 180℃. They are done when a skewer poked through the middle comes out clean.
Story Behind this Recipe
I tried making a cake using a raw apple in the rice cooker, but it turned out too sticky, so I tried making apple muffins! Using one whole apple, I cooked out the moisture fully, so they didn't turn out sticky and they tasted delicious. For a regular cake-like muffin, reduce the amount of apple.
If you add the apple raw, there will be too much moisture, and the muffins will end up being too sticky. The key is to thoroughly cook out the moisture in Step 2!