My son has never said no to a cookie and he (and I) would especially say yes to a bite-sized muffin tin cookie. Rebecca of Cooking With My Kid made some and reports that baking them this way makes them extra soft and chewy inside. Her family declares them "crazy good."
You could try this with your favorite cookie recipe or give Rebecca's a whirl. She made "Crazy Good Choco-Chip Bite Sizers" and you can find the recipe on Cooking With My Kid.
Cooking With My Kid offers tons of inspiration for cooking for your kids and your whole family so take time to look around and say hi to Rebecca.