Two-color cookies

Overview

Recently, I suddenly fell in love with baking cookies, so I started trying all kinds of cookies.

Butter softens at room temperature.
After pouring in the powdered sugar, mix it evenly with a spatula, then beat the butter with a whisk until it turns white.
After beating, add an egg. Mix well.
Pour in the sifted cake flour and stir as needed.
Knead it into a dough that is not sticky.
Reserve about 10 grams of dough and put the rest into the cookie gun. Rotate the cookie gun counterclockwise to make patterns, leaving the middle part empty.
Add 1 gram of cocoa powder to 10 grams of dough and stir evenly until the dough becomes. Dark brown.
Once dark brown, roll into small balls and place in the middle of the cookie. Enter the oven and bake at 150 degrees Celsius and 130 degrees Celsius for 15 minutes.
You're done.