I agree with
@foodpump,
1st. thing is to check your city or state work laws on working interview. Being the litigious society we've become most states require you to almost hire a person to step foot and work in your kitchen.
I would not recommend bringing jacket and tools. That should be a given.
As an owner, I personally feel that expecting for quality product, a perfect appearance, etc. from a chef in a strange kitchen would not be a good indicator of what to expect post hire.
The item or items request can be anything. Do your due diligence and make sure you have all the necessary ingredients for multiple variations of the item.
As
@foodpump states, I would certainly address the knowledge as well as the approximate cost of ingredients and how, and in what volume they would acquire them in.
Personally I could care less what the finished product looks like. My concentration would be focused on the ability to accommodate to the environment. Does this person take control and find ingredients and equipment on their own or do they constantly ask where things are. (a huge red flag for me). Observe organizational skills, priority of prep or mise en place. If you give them the formula, do they ask how many portions you are requesting and do they take the time to actually document/note
on the formula if scaling up or down. Does the formula remain in front of them through the whole task. Observe sanitation habits. Do they clean as they go, or use identical equipment and just go to the plounger with everything of rinse and reuse.
A Pastry Chef will eventually give you, your version the product you desire. The question in my mind is how they get there and is it going to be a profitable event.
Ask for the perfect eclair you used to buy on Sundays with your family as a kid. I think is an expedient road to disappointment, failure, and the potential pass on a superstar.
Just my 2 cents.
I just finished a 5 month hunt for an associate. Very little product knowledge, but has the ability to pull the creativity from the left side of his brain and naturally create a detailed avenue to produce it using the right side of his brain. Analytically, unfragmented, and without distraction. (the ability to stop the creative process with confidence) one ability chefs are losing more of everyday. This past Sunday, I would have enjoyed one of the best fusion dishes I've had in all my travels, but sadly the chef did not stop on his 6th ingredient and created a dish that was so busy my taste but shut down when he went past umami.