I tried every custard shake at Shake Shack. Here's how they rank from worst to best.

The Biscoff Cookie Butter Tiramisu shake.

Gabbi Shaw/Business Insider Over the past year, I've tried and ranked 17 of Shake Shack's shakes.

A late-summer addition was announced in August: a cookie-butter tiramisu shake.

I earned the No.

2 spot in my ranking, behind a classic.

Over the course of the last year, I've embarked on a grueling mission: to taste and rank every shake on Shake Shack 's menu.

Shake Shack has six main milkshake flavors available year-round, plus three or four limited-edition flavors at any given time.

My ranking of 17 Shake Shack flavors, each made with frozen custard, includes classics such as chocolate and vanilla, as well as limited-edition shakes like the Dubai Chocolate Pistachio, which was introduced last summer and brought back this year due to popular demand.

The latest addition to the menu is the Biscoff Cookie Butter Tiramisu shake, which was released in August.

Here's how I ranked them all, from my least favorite to my favorite.

Shake Shack did not respond to a request for comment.

In last place came the strawberry shake.

Gabbi Shaw/Business Insider A strawberry shake costs $6 at my nearest Shake Shack in New York.

It's made with vanilla custard and "real strawberry," according to the website.