Using an electric stand mixer or hand mixer, beat butter and gradually add powdered sugar, vanilla and salt until smooth. At low speed, gradually add the flour, just until combined and the dough comes together. Add dried cranberries, and walnuts either by hand or mixer on low, until they are well incorporated.
Shape dough into a log about 2 inch diameter and wrap tightly with wax paper then saran wrap. If dough is a little sticky, add some flour to the wax paper. Refrigerate for 2 hour until firm.
Preheat oven to 350°F. Remove cookie dough from refrigerator and unwrap paper. Using a sharp knife, slice dough 1/4 to 3/8 inch thick. (To note: if you can the slices a little thicker, then it will require a little longer time in the oven) If dough tends to crumble, leave at room temperature for about 5-10 minutes. Place slices about 1 inch apart on baking sheets.
Bake until lightly golden, 15-20 minutes. Keep an eye on them while they are baking, as shortbread cookies can get overly toasty on the bottom and edges very quickly. Cool on baking sheets for a couple of minutes, and then transfer to a wire rack to cool completely.
OPTIONAL: While they are cooling, to melt chocolate, add chocolate chucks in a bowl over a low boiling pot of water. Stirring as it melts and set aside, and once the cookies are cooled, begin dipping half of the cookie into the melted chocolate and lay on parchment paper to harden.
To store these cookies in an airtight container, laying flat. Can refrigerator for 2 weeks or freeze them for 2-3 months. Enjoy!