Combine butter and powdered sugar in bowl. Beat at medium speed, scraping bowl often, until creamy. Stir in vanilla. Add flour and salt; beat at low speed until well mixed.
Divide dough in half. Shape each half into a disk; flatten slightly. Wrap each in plastic food wrap. Refrigerate 1 hour or until firm.
Heat oven to 300°F.
Roll out dough on lightly floured surface, one-half at a time (keeping remaining dough refrigerated), to 1/8-inch thickness. Cut dough with 1 1/2-inch round cookie cutter. Place 1 inch apart onto ungreased cookie sheets.
Whisk egg white with water in bowl; brush over surface of cookies. Sprinkle with sanding sugar. Bake 10-12 minutes or until set. Cool completely.
Heat apricot preserves in small saucepan over medium-low heat 1-2 minutes or until mixture just begins to bubble. Continue cooking 1 minute. Strain to remove large pieces, if necessary. Cool completely. Spread thin layer of preserves onto unsugared-side of cookie; top with second cookie, sugared-side down. Repeat with remaining cookies.
*Substitute Land O Lakes® Salted Butter.
The sanding sugar dusted over the surface of these cookies gives a pretty sparkle. This sugar contains larger crystals than regular granulated sugar but has the same taste. Keep it on hand to sprinkle over your favorite sugar cookie recipe or roll candied citrus peel in the sanding sugar for a pretty holiday gift.