In a large bowl using an electric hand mixer or in the bowl of a stand mixer fitted with the paddle attachment, beat the softened butter, sifted powdered sugar, and orange zest on medium-high speed until light and fluffy, about 2-3 minutes.

Beat in the vanilla extract until combined.

In a separate medium bowl, whisk together the all-purpose flour, cornstarch, and salt.

With the mixer on low speed, gradually add the dry ingredients to the butter mixture, mixing just until the flour is almost fully incorporated. Be careful not to overmix.

Add the finely chopped dried cranberries and mix on low speed for a few seconds until they are evenly distributed throughout the dough.

Turn the dough out onto a lightly floured surface and divide it in half. Shape each half into a log about 1.5 to 2 inches in diameter. If using, spread the optional granulated or sparkling sugar on a plate and gently roll each log to coat the outside.

Wrap each log tightly in plastic wrap or parchment paper. Refrigerate for at least 1 hour, or until very firm. This step is crucial for preventing the cookies from spreading. The dough can be refrigerated for up to 3 days or frozen for up to 3 months.

Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Unwrap one chilled dough log and use a sharp knife to slice it into 1/4-inch thick rounds. Place the cookies about 1 inch apart on the prepared baking sheets.

Bake for 12-15 minutes, or until the edges are lightly golden. The centers should still look pale. Do not overbake.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.