I'm currently on the mission 'To Kill an Empire" and I've reached the part where I must travel to Solitude and talk to the chef. When I get there she greets me, says some other things, then closes dialogue. This happens over and over, I can't seem to pass this no matter what I try.

have you spoken with the old mage again?

if you have, then try reloading the last autosave when you arrived in solitude.

Umm, what old mage?

the cook your talking about makes you put on a chef hat before you can start cooking. theres a few on the wall in that same room. try that and put one on and then see if she will let you continue

This.

She won't continue unless you look like a chef. Meaning, you must wear the stupid hat. lol Sometimes assassins must work in disguise, this is one of the weaker examples but still necessary.

If she won't continue conversation after you have the Chef's hat on, then I'd try reloading from an earlier save. I personally have never had any problem with any DB quest glitching/bugging, but other quests have been a simple matter of reloading a save and letting the Xbox re-think that particular part of a quest line. This usually gets me past any difficulties that I'm having.

You ARE impersonating a chef, so you should look like one! Radiant Raiments in Solitude sells the chef outfit and hat.

Ok, I tried that and still the issue...Someone mention if I was a vampire(which I am) this glitch would occur, but I'm not about to cure my vampirism. I like being a vampire. It's a part of my character's role play...unless of of course I can become a vampire again.

Ok, I resolved the issued. It was because I was a vampire. I cured myself and everything worked out fine.

Yea I am sort of a role player in some areas, although not so much as a lot of others to eat every day and sleep every night... but my assassin would find and change into different outfits to serve the role I was playing. Like changing into a couriers outfit (stormcloak/imperial) that he was wearing to deliver his message. I also bought an entire chefs outfit complete with shoes before even starting that part of the quest. My assassin relied almost entirely on distance and surprise to get the job done, so I never needed to wear armor. It always made me laugh how much you could look like an assassin, and people wouldn't treat you any differently than if you were wearing street clothes.

If you were on the run from a powerful person, would you let a hooded man in all black wielding a dagger as close to you as a wounded hunter wearing only a bow and some bloodied furs? A good assassin is part con man part hit man, but in this game the name of the game is play how you want to play... so everyone is completely oblivious to who you are, what you say, who you swear allegiance to, what you wear, and what race you are. Skyrims a good game, but there's a reason why people who could play morrowind up until the day oblivion came out are bored just a month or so after skyrim came out. You only have to do the quest once and SOMETIMES twice to see all possible outcomes. No quest seems to have more than 2 outcomes or ways of doing it, most questlines only ask you once to choose between a path during it.

The Vampire Gourmet: "For it is I... The Gourmet!"

Gianna: "I... well I just can't believe that the Gourmet is a vampire, because well... they drink blood. I had you pegged for a wood elf. You see, only someone with knowledge of woodland herbs and cannibalistic tastes would combine..."

She commented on me being a Khajiit aswell. "With all the hair, doesn't that get into the dishes? Seems a bit unhygienic to me..." or something...
Wonder what she has to say about Orcs, then.