Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Cream together the unsalted butter and granulated sugar in a large mixing bowl until light and fluffy, about 3 minutes.

Incorporate the egg yolk, chopped rosemary, and grated Parmesan cheese into the mixture. Stir well to combine.

Gradually add the all-purpose flour and salt to the mixture. Mix gently until just combined.

Roll out the dough on a floured surface to about half an inch thick. Use cookie cutters to create snowflake shapes.

Bake the cookies on the prepared baking sheets for 10-12 minutes, until the edges are golden brown.