Mmmm, dark chocolate, soft, chewy cookies. Excellent choice! I quite enjoyed these cookies. I used about 3 ounces of semi-sweet chocolate and 7 ounces of bittersweet chocolate. I wasn't worried about them not being as tasty if I used all bittersweet, I just had a small stash of semi-sweet chocolate that was getting some age on it. Chocolate, unlike wine (which you can't prove by me) does not generally improve with age. I know the bloom doesn't much affect the taste - but it is just so darned ugly.
At any rate, my only issue with these cookies was the initial chocolate melting. We were to melt the butter, sugar (brown) and chocolate over low heat until it was smooth and shiny. Mine was never really smooth. I could always see the crystals from the sugar in the melted mixture. I gave it some extended time on the burner - over 30 minutes, but I saw no evidence that the crystals were going to turn into shiny smoothness, so I finished mixing the dough with the shiny, but gritty chocolate mixture.
The dough seemed to come together with no issues, I divided it and put the two halves in the refrigerator. After an hour or so I pulled it out and began to make balls of dough. The edges of the dough were rather firm, but the center was totally malleable. The only minor issue I had was pressing down the colder balls of dough. I guess the larger lumps were the correct size because some of my smaller ones did more cracking along the edges than in the middle. In general, my cookies were quite a uniform size and did not develop sway-backed centers - they stayed round and puffy.
In a very few instances when I bite a cookie I get a sensation of sugar and wonder if I really should have tried for a totally smooth melted mixture,but it is rare and it is not an unpleasant taste, just a slightly gritty texture.
I have three dozen in the freezer, gave away another dozen today and have been munching on them pretty regularly. The yield was great - close to sixty cookies