How to Make It
Whisk together the flours, cinnamon, and salt in a bowl.
Beat the butter and granulated sugar in a bowl with an electric mixer on medium-high until light and fluffy, 2 to 3 minutes. Beat in the vanilla. Reduce mixer speed to low and gradually add the flour mixture; stir until just combined. Shape into 2 1-inch-thick disks, wrap in plastic wrap, and refrigerate for at least 2 hours and up to 3 days.
Heat oven to 350° F. Line 2 baking sheets with parchment.
Roll the dough 1/4 inch thick on a floured surface. Using a lightly floured 2-inch cookie cutter or a sharp knife, cut the dough into shapes, flouring the cutter and rerolling the scraps as necessary.
Place the cookies 1-inch apart on the baking sheets. Bake until dry around the edges, 10 to 12 minutes. Let cool slightly on the baking sheets, then transfer to a wire rack to cool completely.
Combine the confectioners’ sugar and 2 to 3 teaspoons water in a bowl. Transfer the mixture to a piping bag or a resealable plastic freezer bag (with a small hole snipped into a corner). Decorate the cookies as desired and let set before serving.