There’s a lot to love about a great rocher cookie—a crisp outer shell, a gooey soft interior, and in this case, salty-sweet cornflakes for crunch. A rocher, which means rock in French, is a meringue-based cookie, and to make them perfectly is all about getting egg whites to form stiff, glossy peaks. The key is to start with an extra clean bowl. Before you get going, wash the bowl of your stand mixer, then wipe down with a mixture of distilled vinegar and water, which breaks down any remaining fat that might be clinging to the bowl from previous recipes. The edible gold is optional, but it makes for a showstopper effect, worthy of any special occasion.