Icebox Butter Cookies
Divide dough in half; form into two 2-inch square logs, each approximately 5 1/2 inches long. Wrap logs in waxed paper; refrigerate until firm, at least 2 hours.
Preheat oven to 350 degrees. Slice dough crosswise, 3/16 inch thick; carefully transfer slices to baking sheets.
If decorating, brush with egg wash, then sprinkle with sugar or sprinkles. Bake until edges are firm (not brown), 10 to 15 minutes. Cool 1 to 2 minutes on baking sheets; cool completely on a rack.
Store finished cookies in an airtight container, up to 2 weeks.