The two main reasons crab cakes fall apart is that there isn't enough filler, or they weren't chilled prior to cooking them. This recipe calls for the cakes to be chilled, but doesn't use a ton of fillers (we want that true crab flavor to come through), so it's essential to chill them. If yours are still falling apart, you could try freezing them for about 15-20 minutes, although you may have to add a little additional baking time. Keep in mind, freshly homemade crab cakes like this are supposed to be tender and flaky, not compact hockey-puck like crab cakes.