PHILADELPHIA (CBS/CNN) – A sweet treat that is super cheesy is being celebrated on Tuesday. National Cheesecake Day is celebrated on July 30 every year.

The simple dessert has several variations, including the New York-style, the Philadelphia-style and even a Chicago-style.

But none of those were the first cheesecake styles. The Greek-style started it all, according to the National Day Calendar.

The Nationals Day Calendar says an ancient Greek physician wrote a book on the art of making cheesecakes thousands of years ago.

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To top off the celebration, some of your favorite restaurants are offering freebies and deals to honor the cheesecake.

White Castle is offering a free slice of cheesecake on a stick with any purchase. Check out the websites Value Offers section to download the coupon.

Cheesecake Factory is offering half-priced slices on your favorite cheesecake flavors to celebrate the day.

All you have to do is buy an adult entree at Maggiano's to get a free cheesecake slice. The offer is available to dine-in customers only.

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