Ask that same experienced gourmand I referenced down below about what distinguishes the perfect macaron, and he’ll tell you that the most important feature of a good macaron is its “foot.” What are “feet” in the context of macarons? They’re the rough, uneven bits on either side of the filling, the bottoms of the disks when they bake up on the sheet. Who ever decided that a macaron must have a foot in order to be great? Who knows? But somebody did, and now we’re all stuck with it. (I’ll have you know, however, that my grandmother’s meatloaf has a distinguishing feature along its edge that I refer to as “the elbow”, the secret to which I shall never divulge). Getting those feet is the obsession of modern macaron makers, as it is an emblem of both skill and cultural awareness. God knows I like to exhibit both of those things as often as I can. So let’s talk feet!
The “foot” of a macaron — as unsightly and uneven as it may appear to the untrained eye — is a factor of the macaron’s rising. The smooth “cap” on the top of the cookie is how it appears when it’s initially piped onto the sheet pan. If a macaron is prepared correctly, that cap will hold its shape, immobile and without cracking, as it heats in the oven. Of course the interior of the macaron is a foam, containing countless bubbles of moisture-laden air. When the air inside those bubbles heats up, they bubbles are going to want to expand. But expand to where? If the cap that surrounds the macaron won’t budge, they’ll have nowhere to go but down. That downward force pushes the cap up, revealing the randomly formed interior of the macaron, otherwise known as the “foot.” Not too complicated really. Anyone who’s ever launched a water rocket as a child can see what’s going on here. But how to create that effect? Better to show you in a tutorial, I think.