I have been experiementing with macarons these last few months, and I have yet to make perfect macarons. Most of the macarons I have made are hollow on the inside. They're so hollow, if I nudge them a bit, the top crust just comes right off. They still taste decent but not what a successful macaron should be like. I don't think I am overbeating my meringue at all. They are always firm and stiff. I have tried whipping a little less than I usually do but still get hollows. I did some research and saw a few people recommend adding a bit of cornstarch to the dry mix. Yep. Cornstarch. This really perplexed me because I always see people saying not to use powdered sugar that contains cornstarch, so how could adding cornstarch prevent hollow macs? I also saw one person use tapioca starch to prevent hollows as well. This time around, I whipped the meringue at a much longer time, but no higher than speed 7 (kitchenaid), which gave me a super stable meringue. I also added cornstarch. I piped the batter out, and they looked super perfect the first few minutes in the oven. Sadly, they came out very wrinkled. The first batch was super wrinkled, but the second batch was less wrinkled, or bumpy even. Not sure if this is because of the silpat for the first batch and the parchment pper for the second hmm. Does anyone know what I did wrong to get these wrinkled macs and how to troubleshoot? Also some help on hollow macs would be appreciated! Thanks