The chocolate chip cookie is no fad. This beloved American treat is a go-to sweet treat, and cookies in the pastry case always sell.

Chocolate chip cookies come in so many different shapes, sizes, thickness, sweetness levels, shades of browning, and textures. They are their own chemistry experiment, for as you play with amount of butter (or other fats -- which each can change a great deal in the cookie's structure), amount and type of sugar, different types of flours, nuts, the temperatures of the dough when placed in the oven, the oven temperature, and even adjusting the baking soda in the recipe can create differences in the spread and the crumb of your cookie.

Baking times and temperatures make a huge difference, and every pastry chef has a laundry list of tricks to get the best version of the chocolate chip cookie. The variables and combination possibilities in chocolate chip cookie recipes are limitless, meaning that we all have a lot of different cookies to taste-test.

See also: Baking with Butter: A Series on Local Pastry

It was very surprising that only four of the six bakeries I stopped by for a chocolate chip cookie had them on the shelf. The two bakeries I went to that didn't have them, told me that I could order chocolate chip, but they don't have them available daily. I don't pick up chocolate chip cookies in a bakery for pleasure, because I like my own variation. However, I do like to taste other chefs chocolate chip cookies, because everyone has their own version, and I want to taste their take on a classic.

Karl's Quality Bakery- There are many eye-catching pastry options in the case at Karl's, that you may almost miss the tray of mixed variety cookies sitting near the cash register. These small cookies run you under a dollar, and with a deep brown exterior, they are best for the crunchy cookie lover, with little chew and goo in the interior of the cookie.

Tammie Coe Cakes - Tammie Coe's chocolate chip cookie is the best of both worlds, offering some crunch around the exterior perimeter of the mammoth cookie, and soft chewiness on the interior. It's a little pricier than the others, but definitely worth the splurge.

Urban Cookies - From the shop that specializes in cookies, you walk in expecting a lot. At Urban Cookies, you will find more unique flavors for their chocolate chip cookie. There is the milk chocolate chip cookie that is mellow in flavor and despite being thin, is very soft. The dark chocolate walnut cookie, which also boasts coconut and oats, is not overly sweet, while bringing some hearty substance and chewiness to the cookie table.

Karsh's Bakery - Tucked in the corner of a nondescript plaza, Karsh's is right out of your foggy memories of trips to the bakery with mom or grandma. Their cookies remind me of the cookies I used to get in the bakeries back on the east coast. Despite being pale in color, and looking like they will be uber crumbly and dry, these cookies are actually very soft and crumbly, but are not for those who are desiring some chewiness. There is a bit of an aftertaste to the cookies that could be explained by using a different fat other than butter, which may be better for those who can't have dairy in their cookies.

Get out and taste some local takes on the ever-popular chocolate chip cookie, or start the experimentation process to create your ultimate chocolate chip cookie. Tastes vary and so do the cookies.

Rachel Miller is a pastry chef and food writer in Phoenix, where she bakes, eats, and single-handedly keeps her local cheese shop in business. You can get more information about her pastry at www.pistolwhippedpastry.com, or on her blog at www.croissantinthecity.com.

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