Today I found out a new baker in my area is using my company name with the work "cookie" added to it. So it's just different enough. Is it worth sending a cease and deist letter, she just started out in June; but I'm completely horrified anyone would do this. What would you do? 

I have an LLC, which extends protection to my name in my state. Not sure what the rules are otherwise.

If she's unimaginative enough that she can't do better than that, is it really worth worrying about? 

Out of curiosity what is your business name? I think what you choose to do depend on how generic or how original your own name is.

For example if your name was 'sugar' and hers was 'sugar cookie' then it would be easy to see how you ended up with similar names just by chance but if your name was 'sweet nothings' and she just wacked cookie on the end of it then it would be easier to think she stole your name. 

I would be so angry if someone local did this. Have you thought about a trademark for your name? I haven't done this yet and haven't looked into it enough but I'm guessing it will be pricey!