I think you and your DH need to stop letting things fester and be open (in a timely manner) with your mil about any concerns that arise.
Different things bother different people - the cake wouldn't bother me - if someone wanted to bake my kid a cake I would jump for joy. I don't do baking. If my mil dropped in unannounced that would probably bother me. My point is your mil isn't a mind reader. If she is continually annoying you chances are it's because you and your DH have danced around the truth for too long.
Best of luck.