Downloading a Delicious Cookie

Cookulus, an app with cookies recipies. Shaminder Dulai for Newsweek

I was washing up the last of the dishes when a little elfin voice behind me shouted: "Cookies!" I dropped the bowl I was rinsing with a loud crash and looked around. I thought I was alone in the kitchen. The voice gleefully shouted again to me: "Cookies!" I looked around me expectantly - I mean, who doesn't like cookies?

It took me a few moments to realize the little voice was coming from my iPad. My first batch of cookies using the Cookulus app was in the oven, and I was quietly reveling in the genius of the app as I washed up. It turned out the app's timer doesn't gently chime to tell you when your cookies are ready: It shouts "Cookies!" like some hyperactive child. Judging by my response, it's quite effective.

Cookulus: Ultimate Chocolate Chip Cookie ($2.99/iTunes) is a magical little app that provides more than 5,200 different chocolate chip cookie recipe variations. It's not exactly cutting edge, having made its debut in the iTunes store in 2010, but it's too wonderful to be overlooked in the avalanche of new apps that appear each day.

The creators - cookbook author Andrew Schloss and entrepreneur Max Minkoff - looked at more than two dozen chocolate chip cookie recipes to arrive at a master recipe - a blueprint for the perfect cookie. They examined how different measurements affect a cookie's outcome. Chewier cookies use more brown sugar and more egg. Thicker cookies have more flour, and cook for less time in a hot oven. Want a thin cookie? Make your ratio of ingredients in favor of more butter, sugar and flour and less egg, then cook it slowly at a cooler temperature than normal. Thankfully, they then developed an algorithm that manipulates the basic recipe to create exactly the cookie you wish, so you don't have to be the one rethinking the ratios in your recipe. In the app, three slider bars allow you to choose exactly how you want your cookie: crispy or soft, chewy or crumbly, thin or thick, and every possible degree of variation in between. As you manipulate the bars, oven temperatures and cooking times rise and fall, sugar and flour proportions shift, and butter and eggs are gained and lost.

So don't be surprised, you lovers of thick, chewy cookies if you are baking cookies at 450 degrees for six minutes. For those desiring cookies that are chewy-middled and thin-like-a saltine (if a saltine were like a Hollywood starlet, thin and tan something to be desired), it's 275 degrees for 29 minutes. If you're not blessed with a digital oven or oven thermometer, you'll just have to get as close to 275 degrees as possible, and between you, me and the Keebler elves, 10 degrees here or there won't make a difference.

I baked six variations, or about 14 dozen cookies. Each variety I made was subtly tweaked to one extreme or other and turned out exactly as imagined, which is more than I can say for anything else in my life. Of the four different recipes the app offers (chocolate chip, whole-wheat chocolate chip, chocolate chocolate chip and walnut chocolate chip), I tried all of them except the walnut ones, because nuts have no place in a chocolate chip cookie. (My editor disagrees, but we remain cordial, if somewhat distant colleagues.)

The app creators made many smart choices: There are more chocolate chips than found in your standard recipe. All recipes use whole, large eggs, so you don't need to measure eggs by weight. You also get to choose your preferred method of measurement, be it metric weight, U.S. weight, U.S. volume or the very, extremely precise volume (which looks like this: 2 cups + 2 Tbsp. + ¼ tsp.). Buy yourself a precision kitchen scale, so you can measure by weight and you will speed the process along. Good-bye to all that scooping and swiping and futzing around that happens when you use measuring cups. Americans may have invented the world's greatest cookie, but they should look to the rest of the world when it comes to measuring ingredients.

The Cookulus app has made me part company with the back-of-the-chips-bag recipe, as well the more than 25 different versions I've squirreled away over the years in my blue plastic Cook Me folder. Half of them are called The Best Chocolate Chip Cookie Recipe in the World. I now know they are wrong. With Cookulus, I not only have the world's best chocolate chip cookie recipe, I have the ability to tweak it to suit my capricious whims and those of my family and guests. A girl needs to be prepared, you know. What if Sherlock comes over and demands his own personalized Cumber-batch of cookies? My oven is hot, Benedict. Cookulus and I are ready for you.