1. Let the butter soften at room temperature and beat with a whisk until smooth
2. Add granulated sugar, powdered sugar and salt, beat until the sugar is dissolved into the butter, the color will become lighter (white) and become relatively fluffy
3. Add the egg liquid and milk in batches and mix well. The egg liquid must be thoroughly blended before adding the next time. Sift into low-gluten flour
4. Use a rubber spatula to stir the flour and butter paste until all the ingredients are combined, do not over-mix
5. Put the batter into a piping bag, and line the baking tray with greased paper. Use a large flower mouth to squeeze out cookies one by one in the baking pan
6. Preheat the oven to 350-360°F and bake for 15 minutes. The periphery of the biscuits will be colored. Turn the baking tray 180 degrees in the middle.