In a large mixing bowl, combine the softened butter and granulated sugar. Using an electric mixer on medium speed, beat until light and fluffy, about 2–3 minutes. Add the vanilla extract and orange zest, and continue mixing until incorporated.

In a separate bowl, whisk together the flour and salt. Gradually add this mixture to the butter mixture, blending just until a crumbly dough forms. Avoid overmixing to preserve the delicate texture of the shortbread.

Gently fold the finely chopped dried cranberries into the dough until evenly distributed. If the dough appears too crumbly, lightly knead it by hand until it comes together.

Divide the dough in half and shape each portion into a log approximately 2 inches in diameter. Wrap each log securely in plastic wrap and refrigerate for at least 1 hour, or until firm. For convenience, the dough can also be chilled overnight or frozen for up to 3 months.

When ready to bake, preheat the oven to 325°F (165°C). Line two baking sheets with parchment paper.

Unwrap the chilled dough and, using a sharp knife, slice into ¼-inch thick rounds. Arrange the slices on the prepared baking sheets, leaving approximately 1 inch between each cookie. Bake for 12–15 minutes, or until the edges begin to turn lightly golden. Avoid overbaking.

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

In a small bowl, whisk together the powdered sugar and freshly squeezed orange juice until smooth. Adjust the consistency by adding additional sugar or juice as needed. Drizzle the glaze over the cooled cookies, and garnish with a light sprinkling of orange zest, if desired.