Preheat your oven to 350°F (175°C) and line two baking trays with parchment paper.

In a large mixing bowl, cream the unsalted butter and granulated sugar together on medium speed for about 2-3 minutes until light and fluffy.

Add the egg yolks and vanilla extract, blending on low speed until fully incorporated.

Gradually add the all-purpose flour and salt, mixing on low speed until large crumbles form.

If the dough is too stiff, add 2 tablespoons of milk and mix until absorbed; adjust with more milk if necessary.

Fit a piping bag with a large star tip, spoon the dough in, and ensure no air pockets remain.

Pipe the dough onto the prepared trays, spacing each cookie about 2 inches apart.

Bake for 13-15 minutes until the edges are lightly golden while keeping soft centers.

Cool the cookies on the baking tray for 5 minutes before transferring them to a wire rack.