Why Did My Swiss Meringue Buttercream Turn Soupy?
There are few moments in baking as disheartening as watching a bowl of beautiful, glossy meringue—whipped to perfect stiff peaks—suddenly deflate into a soupy, broken mess the moment you add the butter. Your heart sinks. You picture your perfectly baked cake layers sitting on the counter, waiting for a frosting that now looks more like a failed custard.