Sparkling Eggnog Sugar Cookies

Line rimless baking sheets with parchment paper or grease; set aside.

In large bowl, beat butter until fluffy; beat in brown sugar until smooth. Beat in egg and rum extract. In separate bowl, whisk together flour, nutmeg, baking powder and salt ; stir into butter mixture, one-third at a time, to make smooth dough. Divide in half; shape into discs. Wrap and refrigerate until firm, about 1 hour. (Make-ahead: Refrigerate for up to 24 hours.)

Between waxed paper or on floured surface, roll out dough to scant 1/4-inch (5 mm) thickness. With 3-inch (8 cm) cookie cutter, cut out shapes, rerolling scraps. With spatula, place cookies, 1 inch (2.5 cm) apart, on prepared pans.

Sparkling Glaze: Whisk egg white with 1 tsp (5 mL) water; brush over shapes. Sprinkle with sugar; press sugar gently.

Bake in top and bottom thirds of 375°F (190°C) oven, rotating and switching pans halfway through, until bottoms are golden, about 10 minutes. Let cool for 2 minutes on pans on racks. Transfer to racks to let cool completely. (Make-ahead: Layer between waxed paper in airtight container and store at room temperature for up to 5 days or freeze for up to 2 weeks.)