Melt the butter in a 2-quart saucepan over low heat. Set aside to cool slightly.

Sift together the flour, kosher salt and baking soda onto a paper plate. 

Pour the butter into your stand mixer's work bowl. Add the sugar and brown sugar and beat with the paddle attachment on medium speed for 2 minutes.

Whisk together the whole egg, the egg yolk, milk and vanilla extract in a measuring cup.

Reduce the mixer speed and slowly add the egg mixture. Mix until thoroughly combined, about 30 seconds.

Integrate the dry ingredients.

Add the chocolate chips.

Chill the dough for 1 hour.

Preheat the oven to 375°F.

Scoop the dough into 1 1/2-ounce portions onto parchment-lined half sheet pans.

Bake for 15 minutes.

Remove from the oven, place on cooling rack before nom