Prepare Your Space: Clear space in your refrigerator and preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone mats.

Cream the Butter and Sugar: In a stand mixer, cream the butter on medium speed until smooth. Gradually add in the sugar and salt until light.

Incorporate Wet Ingredients: Add egg yolks one at a time, mix after each, then add vanilla extract and milk if needed until combined.

Combine the Dry Ingredients: Whisk all-purpose and cake flour together, then gradually add to wet mixture until smooth.

Adjust the Dough Consistency: If too thick, add more milk one tablespoon at a time until it's smooth and pipeable.

Pipe the Cookies: Transfer dough to a piping bag and pipe 2-inch rounds onto lined sheets.

Chill the Cookies: Refrigerate piped cookies for 20-30 minutes to prevent overspreading.

Bake Your Cookies: Bake in the preheated oven for 10-15 minutes until edges are golden.

Cool Before Serving: Let cookies cool on baking sheets for 5 minutes, then transfer to a wire rack to cool completely.