This is generally known as "land contract/contract for deed". People do it all the time. As suggested in another comment, you should consult an attorney. If either you or your mom is hesitant to do that, you should ask yourself what happens to your house and mortgage if (God forbid) your mom were to die? Don't wait to find out. Get an attorney and make sure that it's all ironed out in advance.
Interesting. Looks like a land contract would have the deed be in my Moms name, but we want the deed to be in my name from the start. I know I should consult a lawyer, but do you know if this land contract can be set up this way?