Chill the baking sheet in the refrigerator while preparing the cookie dough.

Cream room temperature European salted butter in a stand mixer until smooth, then add granulated sugar and salt until fluffy.

Add egg yolks, vanilla extract, and whole milk to the mixture and mix until combined.

Whisk together all-purpose flour and cake flour in a separate bowl, then gradually add to the wet mixture until just combined.

Transfer the dough into a piping bag and pipe 2-inch shapes onto the chilled baking sheet. Chill again for 20-30 minutes.

Preheat the oven to 350°F (175°C) and bake for 10-15 minutes until edges are lightly golden.

Cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.