Cream the butter and sugar together; stir in the vanilla.

Sift the flour and salt into the butter mixture and add the rosemary. Blend on low speed just until combined. Do not overmix.

Divide the dough into two equal portions and transfer each portion to a piece of plastic wrap or parchment paper and roll into a cylinder about 2-inches wide. Refrigerate until the dough is firm and thoroughly chilled, at least 1 1/2 hours or up to overnight.

Preheat the oven to 325°F and line two baking sheets with parchment paper.

Using a sharp, thin knife, slice the logs into generous 1/4-inch thick slices and place on the baking sheets about 1-inch apart. Sprinkle the top of each cookie with some of the sparkling sugar.

Bake until the cookies are lightly colored around the edges and crisp, 18-20 minutes. Let the cookies cool on the baking sheets for at least 15 minutes before transferring to a cooling rack to cool completely.