Shaping flavored butter into a log lets you slice off nice round pats. Rolling it evenly can be a little tricky, which is why we turn to a straightedge for help.
First, plop the soft butter down the center of a sheet of plastic wrap.
Then, fold one end of the sheet over the butter. Hold a ruler (or other hard straightedge) against the wrap over the butter, and pull on the lower piece of plastic to produce even pressure that will squeeze the butter into a uniform log.
Finally, grip the ends of the plastic and twist them in opposite directions. tuck them under the butter log to secure it. Chill and slice as needed, or freeze for up to 3 months.