Home bakers may have experienced the frustration of their macaron shells cracking. We thought it might be helpful to share our experience in this matter to help you understand why your macaron shells are cracking and what you can do to prevent it happening.
1. Dry your piped shells before baking
Meringue gets its consistency from the molecules of air trapped in the egg white proteins. During baking, this trapped air in the meringue component of the batter expands. To prevent the batter from expanding, rising up and cracking your shell, the piped shells must be given time to form a protective skin before baking. To encourage this you need to leave your shells out to dry before baking.
Typically, the shells are ready to bake once the batter has turned from a wet glossy look to a dull matt appearance. Putting your shells in the oven at a very low temperature can be a speedier way of reaching the stage where the protective barrier has formed. Or what we do is to preheat the oven 150 °C, put the shells in but immediately reduce the temperature to 0 °C and bake for 11 minutes. After that, turn the heat back up to 135 °C for 13 minutes.
2. Pipe soon after mixing
Piping the macarons quickly after mixing the batter will also help prevent cracking. The texture and integrity of the final batter is at its best while residual heat from the Italian meringue remains. Leaving macaron batter too long before piping can cause the batter to collapse and lose its architecture of trapped air.
3. Check your decorations
Shell decorations, particularly nuts, may compromise the protective skin of the unbaked macaron shell. It may be necessary to bake your shells first, then add any sharp decorations afterwards.
4. Don’t overmix your batter!
If your macaron batter is overmixed this will also cause your shells to crack.
To recap: if your shells keep cracking, the four main things you can try are - mix the batter less, dry the shells for longer before baking, and bake the macaron shells at a lower temperature, undecorated, for longer.