- STIR flour with parmesan, Skor toffee bits and salt in a medium bowl.
- BEAT butter with sugar in a large bowl, using a wooden spoon, until smooth, 1 min. Gradually stir in half of flour mixture, until just combined. Add remaining flour mixture, kneading with your hands, until dough forms a ball.
- DIVIDE dough in half, then roll each portion into a 2-in.-wide log. Wrap each log in waxed paper and twist ends. Chill until firm, 2 hours.
- PREHEAT oven to 350F. Position racks in top and bottom thirds of oven. Line 2 baking sheets with parchment.
- SLICE cookies into 1/4-in. rounds and arrange 2 in. apart on prepared sheets. Cookies will spread as they bake.
- BAKE in top and bottom thirds of oven, switching sheets halfway through, until lightly golden, 15 to 19 min. Leave on sheet for 5 min, then transfer cookies to a rack to cool completely. Repeat with remaining dough.
Cheese grating tips