Add egg yolk and sugar and whisk thoroughly using a hand mixer or kneader.

Add grape seed oil 3 to 4 times and add blue latte 3 to 4 times and mix slowly enough. When adding water such as milk, if it doesn't mix well, it will separate, so it's important to mix thoroughly.

Add the blueberry bean pot and mix well. You can use blueberry jam instead of blueberry bean pot.

Place egg whites in a bowl and whisk in half the sugar.

When the foam rises white, add the rest of the sugar and turn the hand mixer at high speed to make a persistent and firm meringue.

Scoop the meringue into the yolk mixture and mix in a bowl of meringue.

Mix until no meringue is visible, then divide the mixture of strong flour and baking powder into 3 times and mix until no powder is visible.

Pour into a chiffon frame, stir once with chopsticks, and bake at 170 degrees for 25 to 30 minutes. After cooling the baked cake, garnish with whipped cream and blueberries.