I can't recall where exactly I got this recipe, but I'm sure if I wasn't lazy, I could do a "Google" and find the original and tell you where I got it. But, seeing that it is 12:22 and I've only my second dozen cookies in the oven and that I haven't been feeling too well lately, I'm hoping that you'll let me off the hook. In any event, the recipe isn't mine, and the idea isn't original, but I'm filling the "thumbprints" with ganache, and a brandied cherry half-the cherries I brandied myself a couple of years ago.
226 grams butter
272 grams sugar
1 tsp vanilla paste
40 grams yolks
115 grams Dutch cocoa
2 tsp salt
272 grams flour
30 grams cream
Cream together room temperature butter and sugar, with vanilla paste. Add yolks, scraping after adding and mix until incorporated. Add sifted dries, then cream, mixing until dough comes together.
Allow dough to rest. You may chill the dough, but tonight I let it rest on the counter. Yes, laziness overruled.
I portioned my cookies with a #60 scoop, rolled them into balls, rolled the balls in sugar, lined them up, 12 to a half sheet pan lined with a Silpat. I gently flattened each cookie with the palm of my hand, then used the handle of a spoon to make my indentions in the center.
According to my gas oven, at 350ºF, I baked the cookies for 12 minutes, turned, re-pressing the centers gently, then baked them another 5 minutes. You'll have to adjust according to your oven, but the cookies should be set in the center, not doughy.
For the ganache I simply used dark chocolate and heavy cream with a 2:1 ratio. I filled the centers, gently pressed half a cherry in and let them set.