If your homemade snickerdoodle cookies are falling apart, don't panic! It's probably just a simple baking mistake. Chances are, the dough wasn't mixed well enough, which can cause the cookies to be crumbly and fall apart. Or, the cookies might have been undercooked, which can also cause them to be too delicate to hold together. To avoid these problems, make sure to mix the dough thoroughly and bake the cookies for the recommended amount of time. And remember, a little extra butter never hurt anyone (except maybe your waistline).