I had no problems with the coffee versions (shown above). I used espresso powder which I mixed in with the powdered sugar and almond flour. The espresso powder just blended right in as I started folding the beaten egg whites with the almond flour mix. I must have undermixed since the batter didn't spread out much but the result was great. The underside was perfectly dry and smooth, as shown below:The coffee macarons easily slid off the parchment paper. I had a slight problem with the chocolate version though. They all formed the feet and rose quite well but they came out very thin and fragile and some of the tops even collapsed when I took them out of the oven. They were still very moist so I suspected they must be undercooked. The underside wasn't as dry as the coffee ones but I still had no problem peeling them off the paper. I will try to correct the problem by increasing the baking time a little bit next time. The additional cocoa in the recipe must have been the cause but other than that, the texture and the flavors are just great. We usually eat them without any filling although I personally think Nutella (chocolate hazelnut spread) works great as a filling for the ultimate chocolaty macaron sandwich.
Nutella filled chocolate macaron