The process of reverse engineering a recipe requires experiments to vary ingredients, ingredient amounts, mixing procedure, baking temperature and baking time. Having tried a variety of those elements myself, I realized that this recipe lends itself to being a teaching recipe. You may decide to try recipe variations of your choice worthy of consideration in arriving at your version of perfection. Some of the obvious variations are noted in the ingredients list and in the later baking directions.
The key objective is to make a buttery and crisp and thin cookie. But not too buttery because you don't want it to be greasy or oily. The ingredient combination I show in the recipe below, without variations, has some chewiness inside a crisp exterior for the larger size cookies, and you can decide how little or how much of that you want by varying the amounts/ratios of flour, butter, egg white, water, amount of dough per cookie and baking temperature/time. Also the amount of toffee bits, which tend to make the cookie chewy.
I found that the best way to dispense the cookie dough on to the baking sheet is by using a scoop of a specific size. This promotes uniformity. Scoops can be purchased online in different sizes, like 1 tbsp., 2 tbsp, and 3 tbsp., in a set, and they have squeeze handles that make the dough release from and fall out of the scoop and on to the baking sheet.
I describe two different baking periods/temperatures for each baking sheet of cookies, but you might decide to use only one baking period, especially if you are making the smallest size cookie. You use the small addition of water to the dough to make it spread out easily, but be careful how much water (or butter) you use or you will have the same type of result as Alexis Stewart ... a pile of ingredients in the center and a very big diameter cookie. But don't be afraid to experiment.
The combination of the rich buttery taste and the toffee bits in a thin crisp cookie is excellent. For the chocolate I use small pieces of the Callebaut® milk chocolate (type 823NV-132) that I often use in making chocolate candy. You, of course, can easily choose to use a high quality brand of milk chocolate bar, like Lindt®. What a combination! For that matter, you might want to use a high quality semi-sweet or dark chocolate. If you prefer dark chocolate then by all means use that. I also use Callebaut® dark chocolate #811 callets to make a dark chocolate version of this cookie. You can buy the Callebaut® products online at Amazon®.
In my experiments maximum crispness resulted when making the cookies small with the 1 tbsp. dough scoop and 18 minutes of baking time at 300 degrees F. I suggest limiting the amount of toffee bits to 3/4 cup when making the small cookies. Also chop the chocolate pieces/chips so they are no larger than 1/4" squares. You might also try using less butter but use at least 1 3/4 quarter pound sticks of butter.
Okay ... First make the toffee bits, then use them in making the cookies.
TOFFEE BITS
Ingredients: (makes approximately one cup of crushed toffee bits)
3 tbsp. of Butter
1 tbsp. of coconut oil
1/4 cup of Light Brown Sugar
1/3 cup of White Sugar
1/8 tsp. of salt
1 tbsp. of Light Karo® corn syrup
1 tbsp. of Water
Directions:
Put all of the ingredients into a small heavy bottom saucepan.
Bring the mixture to a boil over a small burner on medium heat, stirring until all the ingredients are combined and melted.
Continue to cook on low or very low heat, with gentle stirring, until a candy thermometer reaches almost 280 degrees F. Note that the rise of temperature is faster the higher it gets so do not let the toffee darken/burn from inattention and overheating in the saucepan, ergo, get the toffee saucepan off the heat at about 275 degrees F. The heat in the bottom of the saucepan will quickly elevate the toffee temperature the rest of the way to 280 degrees F, so you don't need to check the temperature after moving the saucepan from the burner.
Immediately pour the toffee onto a parchment paper lined 12" x 17" baking sheet, as thinly as you can (don't dump it into a pile, empty the saucepan over most of the surface of the parchment paper), and allow it to cool.
Once it has cooled to room temperature, break up the toffee into large pieces by hand or by hitting it lightly many places with a wooden kitchen mallet.
Put the toffee pieces into a one quart Ziploc® freezer bag, expel the air and seal it and use a wood kitchen mallet to crush/crumble them into toffee bits.
Now let's proceed with making the cookies ...
TOFFEE MILK/DARK CHOCOLATE COOKIES
If you decide to proceed to make the cookies, be prepared for a whole lot of verbal abuse by chubby women who were formerly svelte before tasting your cookies, or from the same women whose somewhat paunchy husbands have turned into oinkers! We're talking here about serious loss of control for when to stop eating these cookies.
Ingredients: (makes 24 [3 tbsp. of dough] cookies or 36 [2 tbsp. of dough] cookies or around 60 [1 slightly generous tbsp. of dough] cookies)
2 cups of All Purpose Flour (weigh it on your kitchen scale to be accurate ... 10 ounces)
1/4 tsp. of Baking Soda
1/2 tsp. of Sea Salt
1 cup (2 quarter pound sticks) of Butter, softened (you can reduce the amount but only up to 1/4 stick less)
1/2 cup of White Sugar
1/2 cup of Light Brown Sugar
1 egg white
2 tsp. of Pure Vanilla Extract
1 tbsp. of water (you can vary this from one to three tbsp. to get the dough composition you want)
1 cup of Milk Chocolate or Dark Chocolate Chips (or a 50:50 mixture of both)
3/4 cup of Toffee Bits
Directions:
Preheat the oven to 300 degrees F.
Whisk together the flour, baking soda and salt in a one quart bowl.
Use a stand mixer and beat together the butter, brown sugar and white sugar on medium speed for about two minutes.
While continuing to mix, add in the egg white, the water, and then the vanilla and continue mixing for three minutes.
Set the mixer to low speed, then add in 1/2 of the flour mixture, mix for one minute, then add in the other half of the flour mixture and mix for one minute.
Add the chocolate pieces and the toffee bits, then mix for one minute. The dough will be very soft. You can use a rubber spatula to scrape it from the inside sides of the mixing bowl to guarantee proper mixing and later ease of use when filling a scoop with dough.
Now you decide which size of scoop to use, and that will determine whether you need only one baking cycle and one temperature, or, two baking cycles at two different temperatures. The point is the larger cookies require more baking time to come out crisp.
For example, use a 2 tbsp. scoop and a table knife (to avoid having excess dough) to dispense the dough in roughly 1 1/2" mounds on three 12"x 17" parchment paper lined baking sheets, cookies spaced evenly (12 cookies/sheet). If you want thicker and larger cookies then use 3 tbsp. of batter (a 3 tbsp. scoop) for each cookie, putting only eight cookies per sheet. The amount of dough you use per cookie determines how large and thick each cookie will be and also how many you can bake at a time on one baking sheet while avoiding having them crowding each other and distorting the shape.
At this point, if you want, you can freeze the unbaked cookies in the deep freeze, then store the frozen unbaked cookies in Ziploc® freezer bags until you are ready to bake some of them. Otherwise proceed with the baking directions below.
Follow the baking procedure described next for each baking sheet of cookies you decide to bake. Bake one or two sheets of cookies at a time. If you are working with unbaked frozen cookies simply place 8 to 15 of them (depending on size) on the parchment paper on a baking sheet.
Bake each baking sheet of the cookies for 18 or 24 minutes (18 for 1 tbsp. scoop cookies, 24 for 2 tbsp. scoop cookies) on a middle oven shelf, turning the baking sheet 180 degrees after the first half of the total baking time and exchanging shelves if you are baking the cookies two sheets at a time.
Remove the baking sheet(s) from the oven and let the cookies cool on the baking sheet. Do the above baking for all the baking sheets of cookies you have prepared.
Check the cooled cookies for crispness. If you like them the way they are then you have completed making the recipe. If you want more crispness then continue with the instructions given next.
Reset the oven temperature to 250 degrees F. Then put each baking sheet of cookies into the oven, one or two sheets per baking cycle, and let them bake for 10 minutes.
Remove each baking sheet from the oven and let the cookies cool to become firm.
Repeat the above baking step for the other baking sheets of cookies that have had the first baking cycle.
Remove the cookies from the baking sheet(s) carefully with a thin spatula, if necessary cutting through any joined areas first with the spatula. Be careful not to break the cookies when removing them from the baking sheet. Put them on a cooling rack.
Allow the cookies to cool completely to room temperature.
You can store these cookies in an air tight plastic or metal container. Or you can simply let them sit out on a plate for up to a day. They will stay crisp best on a plate if the humidity is low ... otherwise they may begin to soften. Note, however, these cookies are at their peak goodness when freshly made and best later if stored in an air tight container.
Enjoy! Oh, what an understatement! Hey, if you really are going to make and eat these cookies you may as well accompany them with a chilled drink of 4 ounces of milk mixed with one ounce of Kahlua® coffee flavored liquor per person. Pure decadence!