This is a recipe for a flavorful oil cake with sweet potato and black sesame. Cut unpeeled sweet potatoes into 1cm cubes, heat them in the microwave, and mix them into the batter. Mix together beaten eggs, brown sugar, coconut oil, and milk, then sift in cake flour and baking powder, add the black sesame and sweet potato, and mix. Pour the batter into a loaf pan, top with sweet potato and butter, and bake in the oven. The oil-based batter results in a moist and fluffy cake that tastes delicious even when cooled. This simple yet deeply flavorful cake is easy to make and recommended for beginners.