These cookies remind me very much of the Linzer Sables we made a few months ago. This could be because I made mine with ground almonds instead of ground hazelnuts - but I am certainly not complaining about the similarity.
I was shocked by the recipe - could there truly be so few ingredients? No eggs - no liquid, other than the piddling little extracts? Careful rereading showed this to be true. So, I beat and blended and was happily surprised. I suppose I could have done a better job of blending in the nut/flour combo - some of my cookies were rather dry when I was forming them - but all of them (at least the ones I have tried so far) have been excellent to taste. One of the cookies was so dry it just fell apart while cooking. It was, because of this, far more brown the other cookies. As I expected, I liked this very much. Hey - I eat singed toast it should not be a surprise.
I made my cookies a tad on the larger size at first and then realized how low my yield would be so on the last two sheets I made the cookies considerably smaller. I ended up with about 52 cookies, so I did all right in that regard.
I have never made thumbprint cookies before and was wary of pushing a hole through the dough. This concern caused me to make my initial holes too shallow and while baking the cookies rose to make the indentation very faint. While they were cooling on the sheets I went back through them and pushed the dough down to make a deeper indentation. That worked quite well and on the last batch I did much better.
When I was younger my mother would make a cookie called the split second which is very similar to this cookie. There is some difference in the amounts of butter, flour and sugar used, but the recipes are very similar. The main difference between the split second and thumbprint is that you take your split second dough and separate it. You then form each section of dough into a log. Then you press an indentation into the log and fill that indentation with jam. I don't remember my mother ever heating the jam - and these cookies were filled before baking. They are sliced on the diagonal when they come out of the oven. They look like little jewels when they are done. She always said the name came from the speed with which the cookies came together. I found this photo of those cookies on the Taste of Home website.
Jam-filled treats are not my favorite but I filled these with some fantastic blackberry preserves and some three-fruit marmalade so they are rather tasty. I tried melting some chips into one batch (as Dorie did for the small guy thumbprints) but they did not really melt. I think I will make a ganache tomorrow and refill those cookies. I would also like to try some made with a different extract (other than the almond) and fill the cookies with a correspondingly flavored jam. And, of course, I deeply regret not filling any of these with lemon curd. I did think about it, but decided to stick with the fillings I previously discussed. Lemon curd would have been so much more successful than the chips.