John Barricelli shows how to make a versatile shortbread that can be stored in the freezer for up to three months, and he demonstrates two flavor variations.
With an electric mixer, beat butter, sugar, vanilla, and salt until smooth. With mixer on low speed, add flour, mixing just until a dough forms. Stir in desired mix-ins.
Divide dough in half; place each half on a piece of floured waxed or parchment paper. With floured hands, gently roll each into a 1 1/2-inch-diameter log. Dividing evenly, sprinkle logs with desired coating if using, rolling log (to help coating adhere) and pressing in gently. Wrap logs tightly in the paper, and refrigerate until firm, 1 to 1 1/2 hours. (To store longer, wrap log and paper tightly with plastic wrap.)
Preheat oven to 350 degrees. Unwrap logs; with a serrated knife, slice dough 3/8 inch thick (if dough crumbles, leave at room temperature 5 to 10 minutes). Arrange slices, about 1 inch apart, on baking sheets.
Bake until lightly golden around the edges, 15 to 20 minutes. Cool on baking sheets 1 to 2 minutes; transfer to a wire rack to cool completely.