Preheat your oven to a 170-degree Fahrenheit and spray your baking pan with a non-stick cooking spray or butter.
Separate your egg white from the yolk, pour the yolk into a container together with the brown sugar powder. Mix them until you get an even mixture, add water, and corn oil until you get an emulsified mixture.
Add your low gluten flour to the mixture and whisk it until it becomes soft and smooth. Afterward your sesame seeds and stir until it is evenly distributed around the paste.
Add your sweet potato cubes to the mixture, stir continuously until the cubes dissolve. You will get a smooth and thick paste when the sweet potato cubes are evenly stirred.
Mix your egg white and the fine sugar in a different bowl until you get an even mixture. Take 1/3 of this mixture and add it with the egg yolk mixture. Stir them until the mixture is even.
Take the evenly mixed egg yolk mixture and pour it into the egg white mixture. Mix them by using the turning and mixing method, avoid the circular mixing method.
Pour your even mixture into your cake mold. Shake your cake mold gently on the kitchen counter to remove any bubbles present.
Put this cake mold into your preheated oven and bake for 4o minutes. If you want to be sure that the cake is well cooked, you can insert a toothpick into the cake; if the toothpick has no moisture, know that your cake is ready. If there is moisture on the toothpick, you can put the cake back in the oven for another 10 minutes.
After the baking time, take the cake out of the fridge and let it cool down for a while. While the cake is cooling, add fine sugar and brown sugar to your whipped cream, mix them to get an even mixture.
When the cake has cooled off, decorate it with your whipped cream, and top it with your sliced almond.