Mixer on Speed 1 for the entire process

Mix in butter & salt | medium speed till colour is slightly lighten (do not over mix)

Mix in sugar by 2 batches (拌匀就可以了）

Use a spatula to clean the side

Mix in egg yolk & vanilla essence

Mix, clean the side, mix again. (看不见蛋黄）

Using cutting motion lightly mix in flour by 2 batches (do not over mix)

Put mixture into pipping bag & pipe out (挤出曲奇的时候要挤高一点，纹路比较明显）

150° 25mins (must look after it time to time)

Tips 💡