Heat the oven to the specified temperature for the cookie dough you’re using, and line a baking sheet with parchment paper. Print the template and cut out the pieces.
Roll out the dough on a floured surface to ¼-inch thickness. Place the full slipper template atop the dough and use a kitchen knife to cut through the dough around the outer edge. Use a spatula to transfer the dough cutout to the baking sheet
Repeat step 2 until you’ve used up the dough (or have no more space on the baking sheet).
Bake the cookies until the edges turn golden brown, about 7 to 9 minutes. Note: the time will vary between different cookie dough recipes.
Once you’ve removed the cookies from the oven but while they are still on the baking sheet, place the slipper opening template atop each one and use the tip of the kitchen knife to very lightly score the baked dough along the lower edge of the paper.
Use a spatula to transfer the cookies to a cooling rack. Let them cool completely.
Working with one cookie at a time, spread white cookie icing on the portion below the score line. Immediately sprinkle decorating sugar crystals on the icing.
Let the icing harden completely before serving or stacking your glass slipper treats.