Divide dough in half. Roll out each half between two pieces of parchment paper to about 1/8 inch thick. Transfer each half to a baking sheet; cover tightly with plastic wrap. Refrigerate until firm, about 2 hours or overnight.
Preheat oven to 350 degrees, with racks on upper and lower thirds. Remove one sheet of dough from refrigerator, and let stand 1 minute. Using a 3-inch snowflakeshaped cookie cutter, cut out shapes. Place shapes 2 inches apart on parchment- lined baking sheets. Gather together scraps, and reroll as above; chill until firm, 10 to 15 minutes, then cut out more shapes. Repeat process with second sheet of dough.
Decorate cookies with sanding sugar or sprinkles, as desired.
Bake cookies in upper and lower thirds of oven, switching positions of sheets halfway through, until golden around the edges and slightly firm to the touch, about 15 minutes. Let cool on baking sheets 1 minute; transfer to wire racks to cool completely. Store in airtight containers at room temperature, up to 5 days.