Chop walnuts into fine pieces. Sift powdered sugar; set aside. Sift cake flour twice; set aside.

Cream the butter until soft. Add the powdered sugar in 3 parts. Mix well each time until combined.

Mix it with a whisk for 4 mins until white. Scrape off the butter on the inner side of the bowl and mix.

Add salt and mix well. Please change to a spatula. Add vanilla oil and mix well. Add almond flour and mix it until smooth while crushing lumps.

Add all the flour. Fold the flour into the dough while cutting with a spatula. Fold until the lumps are formed.

Scrape off the flour on the inner side of the bowl and mix. Add the chopped walnut. Fold it.

Put the dough on laid plastic wrap. Press it to flatten.

Repeat folding and pressing about 4 times. Shape it square and flatten and ｗrap with the plastic wrap. Let it sit in a fridge for an hour.

An hour later, cut and divide into about 5g each. (If you don't use a kitchen scale, form the dough into round balls with a diameter of 1.5cm / 0.6 inch.)

Roll between the palms of your hands to achieve a rounded ball. Place them in the freezer 30 mins. Preheat an oven to 190℃ / 374 F.

30 mins later, place the rolls 1.5cm / 0.6-inch apart on a baking sheet. Bake it at 170℃ / 338 F for 15-18 mins or until very lightly browned. Let it cool for about 15-20 mins as it is.

Roll cookie balls in powdered sugar. At first, coat it with generous powder.

Roll again after 5 mins, this time tap it lightly to remove the extra powder. Please remove the extra powder on the backside as well. It's all done!