The idea: Bake perfectly round cookies by scooping cookie dough into muffin tins instead of cookie sheets. When the cookies are done baking, their edges will take the tins' circular shapes.
Did it work? Yep! Though, I might be biased because I generally like my cookies more on the cakier and soft side, which baking in tins will also help with. And in case you're wondering, here's the small batch chocolate chip cookie recipe I used.