Prepare the vanilla sugar cookie dough, using any shape cookie cutter you like for cutting the cookies, and bake as instructed. (I used a 2 1/2 inch round fluted cookie cutter.)Cool cookies completely before frosting.
Use a small offset spatula to spread the frosting onto the cookies. Before the frosting crusts over, decorate the cookies with sprinkles and sparkling sugar.
Store the frosted cookies in a single layer in an airtight container at room temperature for up to 3 days, or in the freezer for up to 2 weeks. Unfrosted cookies can be frozen for up to 3-6 months.