In a large bowl, beat together butter, confectioners’ sugar, and vanilla extract with a mixer at medium-high speed until thick and creamy, 3 to 4 minutes, stopping to scrape down sides of bowl.
In a medium bowl, whisk together flour and salt. Gradually add flour mixture to butter mixture, beating just until combined.
Turn out dough onto a lightly floured surface and divide in half. Shape each half into a disk and wrap in plastic wrap. Refrigerate for 30 minutes.
Preheat oven to 350°. Line 2 baking sheets with parchment paper.
Working with one dough portion at at time, unwrap dough and place it on a lightly floured surface. Using a rolling pin, roll out dough to ¼-inch thickness. Using a 2-inch round cutter dipped in flour, cut 28 rounds from dough, and place 2 inches apart on prepared baking sheets, gently rerolling scraps as necessary. Refrigerate for 15 minutes.
Bake until cookie edges are light golden brown, 9 to 10 minutes. Let cool on pans for 2 minutes. Transfer cookies to wire racks, and let cool completely.
Spread 1½ to 2 teaspoons chocolate-hazelnut spread onto flat side of 14 cookies. Top with remaining cookies, flat side down.
Place cookie icing in a piping bag fitted with a small round tip (Wilton #1). On one side of sandwich cookies, pipe antlers and eyes near centers of cookies. Pipe a small dot of cookie icing below eyes for nose, place a candy on top of dot, and press lightly to adhere. Let stand until frosting is dry, at least 2 hours. Store in a single layer in an airtight container at room temperature for up to 3 days.
Notes
*We used Nutella, Betty Crocker Milk Chocolate Decorating Cookie Icing, and M&M’s.
Recipe by TeaTime Magazine at https://teatimemagazine.com/reindeer-shortbread-sandwich-cookies-recipe/