Lightly flour a work surface. Roll the dough to a 1/4-inch thickness.
Use a cookie cutter to cut out the dough.
Place the dough cutouts on a baking sheet lined with parchment paper or a silicone liner. Leave about 2 inches between the cookies. Refrigerate or freeze for about 30 minutes.
Preheat oven to 375°F (190°C).
Make an egg wash by combining the egg and water. Brush over the tops of the cookies. (You won't use all of the egg wash.)
Sprinkle the tops of the cookies with cinnamon-sugar.
Bake 10 to 12 minutes, or until the cookies are golden brown. Cool on the pan on a wire rack for 5 minutes before transferring the cookies directly to a rack to cool completely.
Notes
*Use store-bought cinnamon-sugar or make your own with a ratio of 4:1 sugar to cinnamon. Either granulated sugar or coarse sugar works well.
Store the cookies in an airtight container at room temperature for about 3 days or in the freezer up to 3 months.