Combine the ★ ingredients in a bowl. Mix well, then add the egg.
Add cocoa powder, and mix until you reach an even, smooth consistency. As you stir, press the spatula against the bowl or use a whisk to smooth out lumps.
Add cake flour, and fold into the batter with a few big strokes (No need to blend to an even consistency.) Transfer the batter to a vinyl bag.
Double the bag for good measure, then rub the batter until evenly incorporated. Once it is well blended, form into a log and chill it in the freezer for 20 minutes.
Slice into 5 mm and bake for 19 minutes in an oven preheated to 340F/170C. The baking time varies depending on your oven. You may need to bake for another 5 minutes.
Story Behind this Recipe
One time, when I had a craving for cookies, I realized I was out of butter, so made some with what was on hand. This is the recipe I came up with.
I made these slightly (or considerably?) bitter and less sweet than average cookies. For children, or those who prefer sweet cookies, adjust the amount of sugar to taste. When forming the logs, be sure to use a lot of pressure, and let the air out of the vinyl bag to achieve dense cookies.