Using an electric mixer on medium speed, beat the flour, butter, sugar, salt, and vanilla until combined. The dough will be crumbly but will hold together when pinched. Mix in the cranberries.
Gather the dough into a disc and wrap in plastic wrap. Refrigerate for about 30 minutes.
Preheat oven to 325°F (160°C). Line baking sheets with parchment paper or silicone liners.
Place the dough on a lightly floured surface. Use a floured rolling pin to roll out the dough to a 10-inch square, about 1/4-inch thick. Using a sharp knife, cut the dough into 2-inch squares.
Carefully transfer the squares to the prepared baking sheets. If you like, sprinkle the top of each cookie with a heavy pinch of sanding sugar.
Bake for 22-25 minutes, or until lightly browned. Cool on the pans for about 5 minutes. Then, transfer to wire racks to cool completely.
Notes
Yield: Makes 25 2-inch cookies.
To store/freeze: Store in an airtight container at room temperature up to 4 days or in the freezer up to 3 months.