Preheat oven to 350°F. Line a large baking sheet with parchment paper.

In a large bowl using a hand mixer on medium speed, cream together the butter and granulated sugar until light and fluffy.

Add the egg yolks and vanilla extract. Mix until just combined.

In a separate bowl, whisk together the all-purpose flour, cinnamon, and kosher salt.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Stir in the whole milk until a soft dough forms.

Roll dough into 1-inch balls and place on the prepared baking sheet. Gently flatten each cookie with the back of a fork.

Bake for 10-12 minutes, or until edges are lightly golden. Let cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.