Heat oven to 350degreesF. Open package of cookies; sprinkle cookies with sugar or glitter. Bake cookies as directed on package. Cool completely, about 10 minutes.
For each sandwich cookie, spread 1 tablespoon frosting on bottom of 1 cookie. Top with second cookie, bottom side down; press together gently. Store loosely covered.
These cookies make a great holiday activity for children. Let them decorate the cookies with sugars and glitter. While cookies bake, decorate the tree or have a cup of hot cocoa, then let the children make sandwiches with the cooled cookies and frosting.
Vanilla frosting may be tinted with red or green food coloring, if desired.