In a medium bowl, beat butter and confectioners’ sugar with a mixer at medium speed until fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add vanilla bean paste and zest, beating until combined.
In a medium bowl, whisk together flour and salt. Gradually add flour mixture to butter mixture, beating until combined.
Divide dough in half, and shape into 2 disks. Wrap in plastic wrap. Refrigerate for at least 30 minutes.
Preheat oven to 325°F. Line 2 baking sheets with parchment paper.
On a lightly floured surface, roll each disk of dough to 1⁄4-inch thickness. Using a 21⁄2- inch fluted round cutter, cut dough. Place on prepared pans.
Bake until firm but not browned, 7 to 8 minutes. Let cool completely on wire racks.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/lemon-shortbread-cookies/