¾cup(170 g) unsalted butter, , melted and slightly cooled
¾cup(150 g) packed light brown sugar
½cup(100 g) granulated sugar
1large egg plus 1 egg yolk,, room temperature
2teaspoonspure vanilla extract
1 ¼cups(220 g) semisweet chocolate chips
Line a baking sheet with parchment paper and set aside.
In a medium bowl, whisk together the flour, cornstarch, baking soda and salt. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment (or using a hand mixer), beat on medium speed the melted butter, brown sugar and granulated sugar until light and fluffy, about four minutes. Scrape down the sides of the bowl when necessary. Add the egg, egg yolk and vanilla. Beat until combined, 20 to 30 seconds.
With the mixer on low, slowly add the flour mixture to the dough. Careful not to over beat. With a wooden spoon or rubber spatula, stir in the chocolate chips by hand.
Scoop 1 heaping tablespoon of cookie dough (I use a medium cookie scoop), shape into a ball, and place onto the prepared baking sheet. Repeat placing each ball of cookie dough about 1- to 2-inches apart. Cover baking sheet with plastic wrap and chill in the refrigerator for at least 3 hours (or overnight).2
Preheat oven to 350° F. Remove plastic wrap from baking sheet and bake cookies for 10 to 12 minutes or until the edges start to turn light brown. Cool on the pan for 5 minutes and then transfer to a wire rack to cool completely. Store in an airtight container at room temperature.
Cornstarch helps keep cookies soft and thick, but it can be omitted if you don't have any.
Alternatively, you can refrigerate the dough in the bowl and scoop chilled dough immediately before baking. Dough can stay in the refrigerator for up to 2 days before baking.
Storing chocolate chip cookies: Store cookies in an airtight container at room temperature for up to one week.
Freezing chocolate chip cookie dough: Cookie dough (in the bowl or scooped into balls) can be stored in the freezer for up to 3 months. If frozen in balls, you can bake them directly on the cookie sheet with an increased baking time of 14 minutes.
High altitude adjustments: Reduce baking soda by 1/4 teaspoon. Reduce brown sugar by 2 teaspoons and granulated sugar by 1 teaspoon.
[easyazon_link identifier="B01JTDG084" locale="US" tag="ifyogiablaki-20"]Kitchen scale[/easyazon_link] - weighing ingredients is much more accurate than measuring with cups.
[easyazon_link identifier="B00C0QJY40" locale="US" tag="ifyogiablaki-20"]Hand mixer[/easyazon_link] or [easyazon_link identifier="B00063ULMI" locale="US" tag="ifyogiablaki-20"]stand mixer[/easyazon_link] - an electric mixer is the easiest and most efficient way to combine ingredients evenly.
[easyazon_link identifier="B0000CDVD2" locale="US" tag="ifyogiablaki-20"]Cookie scoop[/easyazon_link] - This handy tool will make even scoops of cookie dough so each cookie bakes evenly.
[easyazon_link identifier="B0049C2S32" locale="US" tag="ifyogiablaki-20"]Cookie sheet[/easyazon_link] - A kitchen staple for baking, a lighter colored baking sheet absorbs less heat and helps the cookies bake evenly.