This tip is brilliant in its simplicity. You just mash the cookie dough into a roughly tubular shape, wrap it in plastic wrap, and then use the paper towel tube like a mold. Refrigerate until firm and then slice the cookies as usual — except with much more cylindrical results!
I think I'll take Chow's tip one step further. I often find that cookie dough softens too much as I cut, so that the last half of the cookies end up squashed instead of round. If I keep the unsliced cookie dough in the mold while slicing and just push it out from the opening as I go, the paper tube should help it keep the bulk of the cookie dough in a circular shape even if it softens.
→ Check Out the Full Video Tip: How to Cut Perfectly Round Cookies from Chow.com