The cracking is most likely due to air bubbles in the batter. You need to bang the cookie sheets really hard on the counter before baking—and a lot harder than you think. When I took macaron class, the pastry chef whacked the trays on the counter with firm force.
i’d recommend you use pastry chef Stella Parks recipe. For a long time she had a website called Brave Tart up that had a section on macarons. It had a cult like following. But she has become a celebrity chef and is now associated with Serious Eats. So she took now her old blog. But someone posted her recipe on Epicurious, with adding their own notes to her instruction. Thank goodness it was preserved for austerity because this really is an excellent recipe. Parks spent years working in a bakery cranking out hundreds of macarons every week. She knows her stuff when it comes to macarons. Heck she knows her stuff when it comes to baking.
Stella Parks macarons recipe as told by a fan
https://www.epicurious.com/recipes/...NaUFlvTk9yTHdzVE9YSVh1LTE4Z2pOVGdrb0tKZGNydDU.