Step 1

In a medium bowl whisk together the flour and baking soda, set aside. Adjust oven rack to the middle position. Heat to 375°F (191ºC).

Step 2

Cut the butter into 14 even-sized pieces. In a medium skillet, melt 10 tablespoons of butter over medium heat, about 2 minutes. Don't let the butter get too hot, just melted. Then stir in the remaining 4 tablespoons of butter until completely melted.

Step 3

In a stand mixer fitted with the whisk attachment, add the melted butter to the mixing bowl. Add the granulated sugar, brown sugar, salt, and vanilla. Whisk on medium speed (setting until combined, 30 seconds.

Step 4

Add the whole egg and yolk to the mixing bowl. Whisk on medium-high speed (setting until smooth with no sugar lumps remaining, about 30 seconds. Let the mixture stand for 3 minutes. Repeat the whisking and resting process 3 more times: 30 seconds mixing at medium-high speed, and 3 minutes of rest. After four total times, the mixture should be thick, smooth, and shiny.

Step 5

Using a rubber spatula or wooden spoon, stir in the flour mixture until just combined, about 1 minute. Stir in 1 ¼ cups of chocolate chips, giving the dough a final stir to ensure no flour pockets remain.

Step 6

Transfer the mixing bowl to the refrigerator or freezer. Chill until the dough firms up, around 65 to 70ºF (18 to 21ºC), about 15 to 30 minutes. The dough should not feel overly sticky.

Step 7

Divide the dough into 16 portions, each about 3 tablespoons (about 60 grams, 2 ounces), and roll into a ball. If the dough starts to warm and get sticky, place it on a sheet tray and refrigerate for 15 minutes.

Step 8

Tear the dough balls in half. Press the two halves together again with the lumpy torn sides facing upward to expose the chips. This will give a more rustic appearance. Shape the sides of the dough back into a circle. If desired, use the remaining ¼ cup of chocolate chips and press some on top, so they pop out of the surface.

Step 9

Arrange dough balls at least 2-inches apart on lined baking sheets, 8 portions per tray. Smaller baking sheets can be used but will require baking in 3 batches. The dough should be room temperature or just below for even cooking, around 65 to 70ºF (18 to 21ºC).

Step 10

Bake one tray at a time in the center position. Bake for 5 minutes, then rotate the baking sheet. Continue to bake until the cookie edges are golden brown and the centers look slightly underdone, about 5 to 7 minutes. The color will continue to darken during cooling. Place the baking sheet on a wire rack and let the cookies cool until they reach room temperature, 20 to 30 minutes. The chips should still be melty. Make sure the oven returns to 375°F (191ºC) before baking the remaining tray.