The Cheesecake Factory

The Cheesecake Factory is a restaurant in Pasadena where Leonard, Sheldon, Raj, and Howard often go to eat.

Originally, Sheldon objected to eating there since at the time, they ate at Big Boy on Tuesdays. However, he eventually changed the schedule and now they eat at The Cheescake Factory every Tuesday. Penny, who works there as a waitress, always serves them, with Sheldon complaining about her "work ethics". Penny occasionally works behind the bar. Bernadette also worked there as a waitress before getting her PhD.

The Cheesecake Factory serves free cheesecake slices on someone's birthday when they come in. However, it is against restaurant policy to give out free nachos.

Penny meets her on-and-off boyfriend Zack Johnson here, who works for a family run company that designed the menus for The Cheesecake Factory.

In addition, The Cheesecake Factory has a walk-in freezer in back, as seen in The Monopolar Expedition, where Leonard, Sheldon, Raj, and Howard simulated Arctic conditions to train for their 3 month expedition to the magnetic north pole.

Background
The Cheesecake Factory as depicted on the show bears little, if any, resemblance to the actual chain of restaurants (including the sole Cheesecake Factory in Pasadena, California) which are typically decorated somewhat classier than the restaurant depicted on the show. The restaurants are usually decorated in neutrals and reds with decor including elements such as (faux) stone columns. Retaurants do not typically have a stage or musical performances in them.

The uniforms depicted on the show also have no connection to the uniforms worn by actual Cheesecake Factory staff.

To date, no explanation has been given for the use of the Cheesecake Factory name but not the visual design of the chain.