Perfect Chocolate Chip Cookies by America's Test Kitchen

Ingredients:
1 3/4 cups flour or 8 3/4 ounces
1/2 teaspoon baking soda
14 tablespoons unsalted butter
1/2 cup granulated sugar or 3 1/2 ounces
3/4 cups packed dark brown sugar or 5 1/4 ounces
1 teaspoon salt
2 teaspoons vanilla
1 large egg
1 large egg yolk
1 1/4  cups chocolate chips

Instructions:
Adjust oven rack to middle position and heat oven to 375 degrees. Line 2 large baking sheets with parchment paper.  Whisk flour and baking soda together in medium bowl; set aside.

Heat 10 tablespoons butter in 10-inch skillet over medium-high heat until melted, about 2 minutes.  Continue cooking, swirling pan constantly until butter is dark golden brown and has nutty aroma, 1 to 3 minutes. Remove skillet from heat and, using heatproof spatula, transfer browned butter to large heatproof bowl.  Stir remaining 4 tablespoons butter into hot butter until completely melted.

Add both sugars, salt, and vanilla to bowl with butter and whisk until fully incorporated.  Add egg and yolk and whisk until mixture is smooth with no sugar lumps remaining, about 30 seconds. Let mixture stand 3 minutes, then whisk for 30 seconds. Repeat process process of resting and whisking 2 more times until mixture is thick, smooth, and shiny.  Using rubber spatula or wooden spoon, stir in flour mixture until just combined, about  1 minute. Stir in chocolate chips.


Divide dough into 16 portions, each about 3 tablespoons. Arrange 2 inches apart on prepared baking sheets, 8 balls per sheet.

Bake cookies 1 tray at a time until cookies are golden brown and still puffy, and edges have begun to set but centers are still soft, 10 to 14 minutes, rotating baking sheet halfway through baking. Transfer baking sheet to wire rack; cool cookies  completely before serving.

High Altitude baking:
Problem: Cookies spread too much in the oven
Solution: Use less sugar.  Increase the oven temperature and decrease the baking time.
Problem: Cookies are too dry.
Solution: Add an extra egg or yolk.