Chill your baking sheets in the refrigerator for about 10 minutes, then line them with parchment paper or silicone mats.

In a stand mixer, cream the room temperature European salted butter, gradually incorporating granulated sugar and salt until light and fluffy.

Add the egg yolks, vanilla extract, and whole milk, mixing until fully blended.

In a separate bowl, whisk together all-purpose flour and cake flour, then gradually fold into the buttery mixture until just combined.

Transfer the dough into a piping bag and pipe 2-inch shapes onto the prepared baking sheets, then chill for 20-30 minutes.

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

Let the cookies cool on the sheets for a few minutes before transferring them to a wire rack.