Preheat oven to 350°F.
Using a stand mixer or a handheld electric mixer, cream butter and both sugars together for about 2 minutes.
1 cup salted butter, softened, ½ cup granulated sugar, 1 cup light brown sugar, packed
Next, add egg, egg yolk, and vanilla, and beat again until smooth.
1 large egg + 1 egg yolk, 2 teaspoons vanilla extract
In a separate bowl, mix all dry ingredients together. With mixer turning at a slow speed, slowly add dry ingredients to wet.
3 cups all purpose flour, sifted, 1 teaspoon baking soda, 1 teaspoon salt, 1 teaspoon cornstarch
When everything is mixed together, add chocolate chips and mix one final time.
2 cups chocolate chips
Roll dough into small balls and place on baking sheet lined with a silicone baking mat or parchment paper.
Bake for 12 minutes or until cookies are light golden brown.
If you want to take your cookies to another level of decadent, after removing from the oven, lightly sprinkle with a little coarse sea salt. Let cool and enjoy!