Here are a few tips:

• Cook only one tray of cookies at a time (in the middle of the oven) since the temperature is different at top of oven than bottom and cookies on top shelf do not spread out as much.  
• It is slightly better to cook on parchment paper than directly on the tray, because you can immediately transfer the entire set off of the hot tray instead of getting impatient and ruining the cookies with a spatular.
• If you have a scale it is more accurate than use the cup measurements.
• One of the main goals of this recipe is to get the butter browned, you will need to have a light colored pan to see this happening. We also found that the CarZito stove needs to be at 6.5/10 in order to brown the butter.
• Make sure to use dark brown sugar instead of light brown sugar for flavor.
• In our CarZito home taste tests, people liked chopped semisweet Lindt chocolate better than Giradelli semisweet chocolate chips.
• We like to add an extra tsp of butter and sugar and use the higher amount of eggs so that we have the option to taste the butter/sugar/egg mixture several times.
• Making the dough days in advance and refrigerating it improves the taste.  It also works well freeze the dough and thaw it the day before cooking.

Ingredients:

• 1.75 cups (8.75 ounces) unbleached all-purpose flour
• 1/2 tsp baking soda
• 14 Tbsp (1.75 sticks) unsalted butter  (if you use salted butter reduce the salt by 1/3 tsp).
• 1/2 cups (3.5 ounces) granulated sugar
• 3/4 cups (5.25 ounces) packed dark brown sugar 
• 1 tsp table salt
• 2 tsp vanilla extract
• 1 large egg
• 1 large egg yolk
• 1.25 cups semisweet chocolate chips or chunks
• 3/4 cups chopped pecans or walnuts – toasted (optional)

Directions: 

1. Adjust oven rack to middle of oven and preheat to 375 degrees.
2. Line 2 large (18″ by 12″ trays) with parchment paper, or three smaller trays.
3. In medium bowl: whisk flour and baking soda together, and set aside.
4. Browning Butter: In large skillet or pan that is not dark bottomed, heat 10 Tbsp of butter over medium-high heat until melted, about 2 minutes. Continue cooking (1-6 minutes) while swirling the pan (continuously) until the butter is dark golden brown and has a nutty aroma.  (On our stove, need 6.5 setting to turn brown) Remove the skillet from the heat and transfer the butter to a large heatproof bowl.  Stir remaining 4 Tbsp butter into hot butter until completely melted.
5. Into bowl with melted butter, add both sugars, the salt, and the vanilla and whisk until fully combined.  Add the egg and the yolk and whisk until the mixture is smooth with no sugar lumps remaining.  
6. Repeat the following procedure 3 times on the butter mixture.  Let mixture stand for 3 minutes, then whisk 30 seconds. After this process the mixture should be thick, smooth, and shiny.
7. Use a wooden spoon or rubber spatula to stir the flour mixture into the large bowl with the butter mixture.  Just stir until barely combined (about 1 minute.)
8. Stir in the chocolate chips (and the nuts if you are using nuts).  Give the dough a final stir to check for unmixed portions.
9. For large cookies divide the dough into 16 portions, each about 3 Tbsps.  Arrange 2 inches apart on parchment covered baking sheets (8 dough balls per large sheet). For medium cookies divide dough into about 24 portions, each about 2 Tbsps.
10. Bake cookies 1 tray at a time until the cookies are golden brown and still puffy, and edges have begun to set but centers are still soft (about 10-14 minutes).  You can rotate the sheets about halfway through baking if you like.  When you are done you can cool the cookies on a wire rack, or at least take the parchment with cookies on it, off the hot baking sheet.
11. The cookies freeze well with layers of parchment paper between layers of cookies.Dry-fry the cinnamon stick, cardamom seeds, star anise, and cloves in a skillet or a wok over low heat. Stir all the ingredients around for 2-3 minutes or until fragrant. Remove from pan.

Source:

Michelle Snider from work gave Jenny an article by Charles Kelsey “The Perfect Chocolate Chip Cookie” describing his attempts on variations on “Toll House Chocolate Chip Cookies” to see if he could get a buttery toffee flavor.  He found from interviewing chiefs and by trying things that the best two options to make the cookies have this flavor are: try refrigerating the dough for a day or two before cooking, or browning the butter and letting it sit.  He liked the browning best. We did some testing of our own at home and made a few modifications (such as the type of chips used).