STEP 1/6
Place at room temperature, gently dissolve the soft butter in a bowl, add the sugar powder and mix well. In the case of Bundang, there may be lumps, so use a sieve. When mixing with a hand mixer, you have to turn it slowly so that the sugar powder doesn't fly away. Add the egg yolk here and mix well. It's better to make the cream shorter. I used the yolk because there are a lot of yolk, but you can use the egg
STEP 5/6
Make icing the cookies while they cool down For icing, mix the amount of lemon juice, sugar powder, and pigments well and put them in a piping bag. You can control the concentration with lemon juice. If you don't have lemon juice, you can use milk.