In a large mixing bowl, beat the softened butter and powdered sugar on medium speed for 2–3 minutes. The mixture should look smooth, creamy, and slightly lighter in color. Scrape down the sides of the bowl as needed.

Add the orange zest and vanilla extract: Beat briefly until evenly incorporated. The mixture should smell strongly of fresh orange.

Add the flour and fine salt in two additions. Mix on low speed just until the dough begins to come together. The mixture may look crumbly at first, but it should hold together when pressed. Avoid overmixing.

Add the finely chopped dried cranberries: Mix on low speed or fold by hand until they are evenly distributed throughout the dough. Large cranberry pieces can make slicing difficult, so break up any obvious clumps.

Divide the dough into two equal portions: Shape each portion into a log about 8 inches long and approximately 2 inches in diameter. Press and roll gently to make the logs as even as possible.

If using the granulated sugar, spread it on a piece of parchment paper. Roll the outside of each dough log in the sugar until lightly coated. This creates a subtle crunchy edge after baking.

Wrap each log tightly in plastic wrap or parchment paper. Refrigerate for at least 1 hour. The dough should become firm enough to slice cleanly without flattening.

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

Unwrap one chilled dough log at a time: Using a sharp knife, cut each log into 16 slices, about ½ inch thick. If the dough cracks slightly around the edges, press it gently back together with your fingers.

Place the cookies on the prepared sheets, leaving about 1 inch between them. They should spread only slightly during baking. If the sliced cookies feel very soft, refrigerate the tray for 10 minutes before baking.

Bake one sheet at a time for 14–16 minutes . The centers should remain pale while the bottom edges turn lightly golden. Do not wait for the tops to brown deeply; overbaking can make shortbread dry.

Let the cookies cool on the baking sheet for 5 minutes. Transfer them carefully to a wire rack and cool for another 20 minutes. They will become firmer and crisper as they cool.