I have tried to make chocolate macarons several times now. Each time I get a flat cookie (no feet) with a cracked top. I've tried baking them at 325 as well as 300 F. Each time, around 4-6 minutes in the oven, they begin to crack. I tried doubling the cookie sheets and leaving one empty cookie sheet at the bottom shelf. I also have an oven thermometer, so I know my oven temperature is correct.
I used aged egg whites ( at least 24 hours old) and I let them dry for 30-40 minutes before putting them in the oven.
This is what they look like after baking:
I'm using the recipe from joy of baking (https://www.joyofbaking.com/frenchmacarons/ChocolateMacaronsRecipe.html)
Thank you very much