A timeless favorite, jam thumbprints are a staple of bake sales and cookie swaps. Their jewel-like centers make them an eye-catching option, and the contrast between the fruity, plush jam and a rich, buttery, crisp cookie makes them hard to resist. Recipes tradition- ally call for plunging your thumb into balls of dough to make room for the filling, hence the name. We kept our thumbs out of our thumbprints and instead used the bottom of a greased 1-teaspoon measure to ensure even craters. When we added the jam to the indentations before baking, the sugars caramelized and the centers became sticky and leathery; but jam added after baking was too loose. After a bit of trial and error, we discovered the key to success: reshaping the thumbprints halfway through baking. Re-forming the indentations before the cookies were completely set meant we could fill them with a generous amount of jam, and adding the jam partway through baking resulted in a filling that was married to the cookie and set just enough, Any seedless jam can be used.